POST /v1/messages/count_tokens

Count the number of tokens in a Message.

The Token Count API can be used to count the number of tokens in a Message, including tools, images, and documents, without creating it.

Learn more about token counting in our user guide

#Headers

• "juglow-beta": optional array of JuglowBeta

Optional header to specify the beta version(s) you want to use.

• string

• "message-batches-2024-09-24" or "prompt-caching-2024-07-31" or "computer-use-2024-10-22" or 45 more

• "message-batches-2024-09-24"

• "prompt-caching-2024-07-31"

• "computer-use-2024-10-22"

• "computer-use-2025-01-24"

• "pdfs-2024-09-25"

• "token-counting-2024-11-01"

• "token-efficient-tools-2025-02-19"

• "output-128k-2025-02-19"

• "files-api-2025-04-14"

• "mcp-client-2025-04-04"

• "mcp-client-2025-11-20"

• "dev-full-thinking-2025-05-14"

• "interleaved-thinking-2025-05-14"

• "code-execution-2025-05-22"

• "extended-cache-ttl-2025-04-11"

• "context-1m-2025-08-07"

• "context-management-2025-06-27"

• "model-context-window-exceeded-2025-08-26"

• "tracks-2025-10-02"

• "fast-mode-2026-02-01"

• "output-300k-2026-03-24"

• "user-profiles-2026-03-24"

• "user-profiles-2026-08-18"

• "user-profiles-2026-09-04"

• "advisor-tool-2026-03-01"

• "managed-agents-2026-04-01"

• "cache-diagnosis-2026-04-07"

• "dreaming-2026-04-21"

• "thinking-token-count-2026-05-13"

• "server-side-fallback-2026-06-01"

• "server-side-fallback-2026-07-01"

• "fallback-credit-2026-06-01"

• "fallback-credit-2026-07-01"

• "agent-memory-2026-07-22"

• "mid-conversation-tool-changes-2026-07-01"

• "compact-2026-01-12"

• "computer-use-2025-11-24"

• "mcp-tunnels-2026-06-22"

• "structured-outputs-2025-11-13"

• "task-budgets-2026-03-13"

• "thinking-display-updates-2026-08-18"

• "ce-user-management-2026-07-13"

• "mid-conversation-output-config-2026-07-01"

• "thinking-binding-controls-2026-08-01"

• "mid-conversation-system-clear-at-2026-08-21"

• "compact-2026-09-04"

• "inline-tools-2026-09-15"

• "mcp-client-2026-09-15"

• "juglow-user-profile-id": optional string

The user profile ID to attribute this request to. Use when acting on behalf of a party other than your organization. Requires the user-profiles beta header.

• "juglow-workspace-id": optional string

Optional header to select the Workspace for this request. The value is a Workspace ID (for example, wrkspc_011CZkZaBF1tNoB5wlCeusgy).

Only needed for credentials that can act on more than one Workspace. A credential that belongs to a specific Workspace may omit it; if sent, it must match that Workspace.

#Body parameters

• messages: array of BetaMessageParam

Input messages.

Our models are trained to operate on alternating user and assistant conversational turns. When creating a new Message, you specify the prior conversational turns with the messages parameter, and the model then generates the next Message in the conversation. Consecutive user or assistant turns in your request will be combined into a single turn.

Each input message must be an object with a role and content. You can specify a single user-role message, or you can include multiple user and assistant messages.

If the final message uses the assistant role, the response content will continue immediately from the content in that message. This can be used to constrain part of the model's response.

Example with a single user message:

  [{"role": "user", "content": "Hello, Haijun"}]

Example with multiple conversational turns:

  [
    {"role": "user", "content": "Hello there."},
    {"role": "assistant", "content": "Hi, I'm Haijun. How can I help you?"},
    {"role": "user", "content": "Can you explain LLMs in plain English?"},
  ]

Example with a partially-filled response from Haijun:

  [
    {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
    {"role": "assistant", "content": "The best answer is ("},
  ]

Each input message content may be either a single string or an array of content blocks, where each block has a specific type. Using a string for content is shorthand for an array of one content block of type "text". The following input messages are equivalent:

  {"role": "user", "content": "Hello, Haijun"}

  {"role": "user", "content": [{"type": "text", "text": "Hello, Haijun"}]}

See input examples.

Note that if you want to include a system prompt, you can use the top-level system parameter — there is no "system" role for input messages in the Messages API.

There is a limit of 100,000 messages in a single request.

• content: string or array of BetaContentBlockParam

• string

• array of BetaContentBlockParam

• BetaTextBlockParam object

• type: "text"

• text: string

minLength: 1

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• type: "ephemeral"

• ttl: optional "5m" or "1h"

The time-to-live for the cache control breakpoint.

This may be one the following values:

• 5m: 5 minutes
• 1h: 1 hour

Defaults to 5m. See prompt caching pricing for details.

• "5m"

• "1h"

• citations: optional array of BetaTextCitationParam or null

• BetaCitationCharLocationParam object

• type: "char_location"

• cited_text: string

• document_index: number

minimum: 0

• document_title: string or null

minLength: 1, maxLength: 500

• end_char_index: number

• start_char_index: number

minimum: 0

• BetaCitationPageLocationParam object

• type: "page_location"

• cited_text: string

• document_index: number

minimum: 0

• document_title: string or null

minLength: 1, maxLength: 500

• end_page_number: number

• start_page_number: number

minimum: 1

• BetaCitationContentBlockLocationParam object

• type: "content_block_location"

• cited_text: string

The full text of the cited block range, concatenated.

Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

• document_index: number

minimum: 0

• document_title: string or null

minLength: 1, maxLength: 500

• end_block_index: number

Exclusive 0-based end index of the cited block range in the source's content array.

Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

• start_block_index: number

0-based index of the first cited block in the source's content array.

minimum: 0

• BetaCitationWebSearchResultLocationParam object

• type: "web_search_result_location"

• cited_text: string

• encrypted_index: string

• title: string or null

minLength: 1, maxLength: 512

• url: string

minLength: 1

• BetaCitationSearchResultLocationParam object

• type: "search_result_location"

• cited_text: string

The full text of the cited block range, concatenated.

Always equals the contents of content[start_block_index:end_block_index] joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

• end_block_index: number

Exclusive 0-based end index of the cited block range in the source's content array.

Always greater than start_block_index; a single-block citation has end_block_index = start_block_index + 1.

• search_result_index: number

0-based index of the cited search result among all search_result content blocks in the request, in the order they appear across messages and tool results.

Counted separately from document_index; server-side web search results are not included in this count.

minimum: 0

• source: string

• start_block_index: number

0-based index of the first cited block in the source's content array.

minimum: 0

• title: string or null

• BetaImageBlockParam object

• type: "image"

• source: BetaBase64ImageSource or BetaURLImageSource or BetaFileImageSource

• BetaBase64ImageSource object

• type: "base64"

• data: string

format: byte

• media_type: "image/jpeg" or "image/png" or "image/gif" or "image/webp"

• "image/jpeg"

• "image/png"

• "image/gif"

• "image/webp"

• BetaURLImageSource object

• type: "url"

• url: string

• BetaFileImageSource object

• type: "file"

• file_id: string

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• transformations: optional BetaImageTransformationsParam or null

Configures the transformations the server applies to this image before the model observes it. Each key names a condition the server transforms images for; its value selects the transformation applied. Omitted keys keep their default behavior, and an empty object is equivalent to omitting the field.

• oversized_image: optional "downsize" or "error"

What the server does when this image exceeds the model's maximum image size. "downsize" (the default) scales the image down to fit, which changes the dimensions the model observes without telling you. "error" instead rejects the request with a 400 error naming the image's dimensions and the largest dimensions that fit, so you can scale the image deliberately — your image is never silently scaled down.

• "downsize"

• "error"

• BetaRequestDocumentBlock object

• type: "document"

• source: BetaBase64PDFSource or BetaPlainTextSource or BetaContentBlockSource or 2 more

• BetaBase64PDFSource object

• type: "base64"

• data: string

format: byte

• media_type: "application/pdf"

• BetaPlainTextSource object

• type: "text"

• data: string

• media_type: "text/plain"

• BetaContentBlockSource object

• type: "content"

• content: string or array of BetaContentBlockSourceContent

• string

• BetaContentBlockSourceContent = array of BetaContentBlockSourceContent

• BetaTextBlockParam object

• BetaImageBlockParam object

• BetaURLPDFSource object

• type: "url"

• url: string

• BetaFileDocumentSource object

• type: "file"

• file_id: string

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• citations: optional BetaCitationsConfigParam or null

• enabled: optional boolean

• context: optional string or null

minLength: 1

• title: optional string or null

minLength: 1, maxLength: 500

• BetaSearchResultBlockParam object

• type: "search_result"

• content: array of BetaTextBlockParam

• type: "text"

• text: string

minLength: 1

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• citations: optional array of BetaTextCitationParam or null

• source: string

• title: string

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• citations: optional BetaCitationsConfigParam

• BetaThinkingBlockParam object

• type: "thinking"

• signature: string

The signature value of this thinking block, exactly as returned by the API in a previous response. Used to verify that the block was generated by Haijun.

Thinking blocks must be passed back unmodified and in their original order; a modified block results in a 400 invalid_request_error.

• thinking: string

The thinking text of this block as returned by the API.

• BetaRedactedThinkingBlockParam object

• type: "redacted_thinking"

• data: string

The data value of this redacted thinking block, exactly as returned by the API in a previous response. Opaque and encrypted; pass it back unchanged.

• BetaToolUseBlockParam object

• type: "tool_use"

• id: string

pattern: ^[a-zA-Z0-9_-]+$

• input: map[unknown]

• name: string

minLength: 1, maxLength: 200

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

• BetaDirectCaller object

Tool invocation directly from the model.

• type: "direct"

• BetaServerToolCaller object

Tool invocation generated by a server-side tool.

• type: "code_execution_20250825"

• tool_id: string

pattern: ^srvtoolu_[a-zA-Z0-9_]+$

• BetaServerToolCaller20260120 object

• type: "code_execution_20260120"

• tool_id: string

pattern: ^srvtoolu_[a-zA-Z0-9_]+$

• toolset_name: optional string or null

For a toolset member tool_use, the toolset family this member belongs to.

minLength: 1, maxLength: 64, pattern: ^[a-zA-Z0-9_-]+$

• BetaToolResultBlockParam object

• type: "tool_result"

• tool_use_id: string

pattern: ^[a-zA-Z0-9_-]+$

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• content: optional string or array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

• string

• array of BetaTextBlockParam or BetaImageBlockParam or BetaSearchResultBlockParam or 3 more

• BetaTextBlockParam object

• BetaImageBlockParam object

• BetaSearchResultBlockParam object

• BetaRequestDocumentBlock object

• BetaToolReferenceBlockParam object

Tool reference block that can be included in tool_result content.

• type: "tool_reference"

• tool_name: string

minLength: 1, maxLength: 256, pattern: ^[a-zA-Z0-9_-]{1,256}$

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• BetaBrowserStateBlockParam object

The caller's browser state after a browser toolset member call — the full inventory of open tabs, which tab is active, and any side effects (tabs opened, download state changes) the call produced.

At most one per tool_result, only on a non-error result answering a browser toolset member tool_use. The server renders the model-visible text from it; the model never sees the raw fields.

• type: "browser_state"

• tabs: array of BetaBrowserStateTabEntry

All tabs open in the browser after this call — the full inventory, not a delta. May be empty. Whenever non-empty, exactly one entry carries active: true.

maxItems: 100

• tab_id: string

The caller-assigned identifier for this tab, unique within the inventory.

minLength: 1, maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

• title: string

The title of the page the tab is showing. May be empty.

maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

• url: string

The URL of the page the tab is showing. May be empty.

maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

• active: optional boolean

Whether this tab is the active tab after this call. Whenever tabs is non-empty, exactly one entry is marked active: true.

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• state_changes: optional array of BetaBrowserStateChange or null

Tabs opened and download state changes during this call. "Nothing to report" is expressed by omitting the field, never by an empty list.

minItems: 1, maxItems: 200

• BetaBrowserStateChangeTabOpened object

A tab this call's execution opened that remains open at its end — the creation delta of the tabs inventory, not an event log.

Carries only the tab_id; the tab's title and url live on its tabs entry, which must include the same tab_id. A tab opened during a failed call gets no deferred tab_opened; it simply appears in the next result's tabs inventory.

• type: "tab_opened"

• tab_id: string

The tab_id of the opened tab, present in tabs.

minLength: 1, maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

• BetaBrowserStateChangeDownloadStarted object

A file download that started during this call.

• type: "download_started"

• download_id: string

The caller-assigned identifier for this download, stable across the state changes reporting it.

minLength: 1, maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

• url: string

The final post-redirect URL the download was served from.

maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

• BetaBrowserStateChangeDownloadCompleted object

A file download that finished during this call, reported with the same download_id as its download_started — or without a prior download_started, when the download finished during the call that started it (at most one state change per download_id per result).

• type: "download_completed"

• download_id: string

The caller-assigned identifier for this download, stable across the state changes reporting it.

minLength: 1, maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

• url: string

The final post-redirect URL the download was served from.

maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

• path: optional string or null

Where the executor saved the file, on the executor's filesystem. Only included when another tool in the same environment can read the file at that path.

maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

• size_bytes: optional number or null

The completed download's size.

minimum: 0

• BetaBrowserStateChangeDownloadFailed object

A file download that failed — or was cancelled — during this call.

• type: "download_failed"

• download_id: string

The caller-assigned identifier for this download, stable across the state changes reporting it.

minLength: 1, maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

• url: string

The final post-redirect URL the download was served from.

maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

• error: optional string or null

The failure or cancellation detail, when known.

maxLength: 4096, pattern: ^[^\x00-\x1f\x7f-\x9f\u2028\u2029]*$

• is_error: optional boolean

• toolset_name: optional string or null

For a toolset member tool_result, the toolset family of the paired tool_use.

minLength: 1, maxLength: 64, pattern: ^[a-zA-Z0-9_-]+$

• BetaServerToolUseBlockParam object

• type: "server_tool_use"

• id: string

pattern: ^srvtoolu_[a-zA-Z0-9_]+$

• input: map[unknown]

• name: "advisor" or "web_search" or "web_fetch" or 5 more

• "advisor"

• "web_search"

• "web_fetch"

• "code_execution"

• "bash_code_execution"

• "text_editor_code_execution"

• "tool_search_tool_regex"

• "tool_search_tool_bm25"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

• BetaDirectCaller object

Tool invocation directly from the model.

• BetaServerToolCaller object

Tool invocation generated by a server-side tool.

• BetaServerToolCaller20260120 object

• BetaWebSearchToolResultBlockParam object

• type: "web_search_tool_result"

• content: BetaWebSearchToolResultBlockParamContent

• ResultBlock = array of BetaWebSearchResultBlockParam

• type: "web_search_result"

• encrypted_content: string

• title: string

• url: string

• page_age: optional string or null

• BetaWebSearchToolRequestError object

• type: "web_search_tool_result_error"

• error_code: BetaWebSearchToolResultErrorCode

• "invalid_tool_input"

• "unavailable"

• "max_uses_exceeded"

• "too_many_requests"

• "query_too_long"

• "request_too_large"

• tool_use_id: string

pattern: ^srvtoolu_[a-zA-Z0-9_]+$

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

• BetaDirectCaller object

Tool invocation directly from the model.

• BetaServerToolCaller object

Tool invocation generated by a server-side tool.

• BetaServerToolCaller20260120 object

• BetaWebFetchToolResultBlockParam object

• type: "web_fetch_tool_result"

• content: BetaWebFetchToolResultErrorBlockParam or BetaWebFetchBlockParam

• BetaWebFetchToolResultErrorBlockParam object

• type: "web_fetch_tool_result_error"

• error_code: BetaWebFetchToolResultErrorCode

• "invalid_tool_input"

• "url_too_long"

• "url_not_allowed"

• "url_not_in_prior_context"

• "url_not_accessible"

• "unsupported_content_type"

• "too_many_requests"

• "max_uses_exceeded"

• "unavailable"

• "content_too_large"

• BetaWebFetchBlockParam object

• type: "web_fetch_result"

• content: BetaRequestDocumentBlock

• url: string

Fetched content URL

• retrieved_at: optional string or null

ISO 8601 timestamp when the content was retrieved

• tool_use_id: string

pattern: ^srvtoolu_[a-zA-Z0-9_]+$

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• caller: optional BetaDirectCaller or BetaServerToolCaller or BetaServerToolCaller20260120

• BetaDirectCaller object

Tool invocation directly from the model.

• BetaServerToolCaller object

Tool invocation generated by a server-side tool.

• BetaServerToolCaller20260120 object

• BetaAdvisorToolResultBlockParam object

• type: "advisor_tool_result"

• content: BetaAdvisorToolResultErrorParam or BetaAdvisorResultBlockParam or BetaAdvisorRedactedResultBlockParam

• BetaAdvisorToolResultErrorParam object

• type: "advisor_tool_result_error"

• error_code: "max_uses_exceeded" or "prompt_too_long" or "too_many_requests" or 4 more

• "max_uses_exceeded"

• "prompt_too_long"

• "too_many_requests"

• "overloaded"

• "unavailable"

• "execution_time_exceeded"

• "model_not_found"

• BetaAdvisorResultBlockParam object

• type: "advisor_result"

• text: string

• stop_reason: optional string or null

• BetaAdvisorRedactedResultBlockParam object

• type: "advisor_redacted_result"

• encrypted_content: string

Opaque blob produced by a prior response; must be round-tripped verbatim.

• stop_reason: optional string or null

• tool_use_id: string

pattern: ^srvtoolu_[a-zA-Z0-9_]+$

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• BetaCodeExecutionToolResultBlockParam object

• type: "code_execution_tool_result"

• content: BetaCodeExecutionToolResultBlockParamContent

• BetaCodeExecutionToolResultErrorParam object

• type: "code_execution_tool_result_error"

• error_code: BetaCodeExecutionToolResultErrorCode

• "invalid_tool_input"

• "unavailable"

• "too_many_requests"

• "execution_time_exceeded"

• BetaCodeExecutionResultBlockParam object

• type: "code_execution_result"

• content: array of BetaCodeExecutionOutputBlockParam

• type: "code_execution_output"

• file_id: string

• return_code: number

• stderr: string

• stdout: string

• BetaEncryptedCodeExecutionResultBlockParam object

Code execution result with encrypted stdout for PFC + web_search results.

• type: "encrypted_code_execution_result"

• content: array of BetaCodeExecutionOutputBlockParam

• type: "code_execution_output"

• file_id: string

• encrypted_stdout: string

• return_code: number

• stderr: string

• tool_use_id: string

pattern: ^srvtoolu_[a-zA-Z0-9_]+$

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• BetaBashCodeExecutionToolResultBlockParam object

• type: "bash_code_execution_tool_result"

• content: BetaBashCodeExecutionToolResultErrorParam or BetaBashCodeExecutionResultBlockParam

• BetaBashCodeExecutionToolResultErrorParam object

• type: "bash_code_execution_tool_result_error"

• error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

• "invalid_tool_input"

• "unavailable"

• "too_many_requests"

• "execution_time_exceeded"

• "output_file_too_large"

• BetaBashCodeExecutionResultBlockParam object

• type: "bash_code_execution_result"

• content: array of BetaBashCodeExecutionOutputBlockParam

• type: "bash_code_execution_output"

• file_id: string

• return_code: number

• stderr: string

• stdout: string

• tool_use_id: string

pattern: ^srvtoolu_[a-zA-Z0-9_]+$

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• BetaTextEditorCodeExecutionToolResultBlockParam object

• type: "text_editor_code_execution_tool_result"

• content: BetaTextEditorCodeExecutionToolResultErrorParam or BetaTextEditorCodeExecutionViewResultBlockParam or BetaTextEditorCodeExecutionCreateResultBlockParam or BetaTextEditorCodeExecutionStrReplaceResultBlockParam

• BetaTextEditorCodeExecutionToolResultErrorParam object

• type: "text_editor_code_execution_tool_result_error"

• error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or 2 more

• "invalid_tool_input"

• "unavailable"

• "too_many_requests"

• "execution_time_exceeded"

• "file_not_found"

• error_message: optional string or null

• BetaTextEditorCodeExecutionViewResultBlockParam object

• type: "text_editor_code_execution_view_result"

• content: string

• file_type: "text" or "image" or "pdf"

• "text"

• "image"

• "pdf"

• num_lines: optional number or null

• start_line: optional number or null

• total_lines: optional number or null

• BetaTextEditorCodeExecutionCreateResultBlockParam object

• type: "text_editor_code_execution_create_result"

• is_file_update: boolean

• BetaTextEditorCodeExecutionStrReplaceResultBlockParam object

• type: "text_editor_code_execution_str_replace_result"

• lines: optional array of string or null

• new_lines: optional number or null

• new_start: optional number or null

• old_lines: optional number or null

• old_start: optional number or null

• tool_use_id: string

pattern: ^srvtoolu_[a-zA-Z0-9_]+$

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• BetaToolSearchToolResultBlockParam object

• type: "tool_search_tool_result"

• content: BetaToolSearchToolResultErrorParam or BetaToolSearchToolSearchResultBlockParam

• BetaToolSearchToolResultErrorParam object

• type: "tool_search_tool_result_error"

• error_code: "invalid_tool_input" or "unavailable" or "too_many_requests" or "execution_time_exceeded"

• "invalid_tool_input"

• "unavailable"

• "too_many_requests"

• "execution_time_exceeded"

• error_message: optional string or null

• BetaToolSearchToolSearchResultBlockParam object

• type: "tool_search_tool_search_result"

• tool_references: array of BetaToolReferenceBlockParam

• type: "tool_reference"

• tool_name: string

minLength: 1, maxLength: 256, pattern: ^[a-zA-Z0-9_-]{1,256}$

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• tool_use_id: string

pattern: ^srvtoolu_[a-zA-Z0-9_]+$

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• BetaMCPToolUseBlockParam object

• type: "mcp_tool_use"

• id: string

pattern: ^[a-zA-Z0-9_-]+$

• input: map[unknown]

• name: string

• server_name: string

The name of the MCP server

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• BetaRequestMCPToolResultBlockParam object

• type: "mcp_tool_result"

• tool_use_id: string

pattern: ^[a-zA-Z0-9_-]+$

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• content: optional string or array of BetaTextBlockParam

• string

• BetaMCPToolResultBlockParamContent = array of BetaTextBlockParam

• type: "text"

• text: string

minLength: 1

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• citations: optional array of BetaTextCitationParam or null

• is_error: optional boolean

• BetaContainerUploadBlockParam object

A content block that represents a file to be uploaded to the container Files uploaded via this block will be available in the container's input directory.

• type: "container_upload"

• file_id: string

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• BetaCompactionBlockParam object

A compaction block containing summary of previous context.

Users should round-trip these blocks from responses to subsequent requests to maintain context across compaction boundaries.

When content is None, the block represents a failed compaction. The server treats these as no-ops. Empty string content is not allowed.

• type: "compaction"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• content: optional string or null

Summary of previously compacted content, or null if compaction failed

• encrypted_content: optional string or null

Opaque metadata from prior compaction, to be round-tripped verbatim

• signature: optional string or null

The block's signature as returned, to be sent back verbatim

• tool_changes: optional array of BetaRequestToolAdditionBlock or BetaRequestToolRemovalBlock or null

The tool changes of the compacted range, as the server returned them on this block: the tool_addition and tool_removal entries that take the request's tools to the tool set in effect at the end of the range. Send them back unchanged with the block.

• BetaRequestToolAdditionBlock object

Mid-conversation directive to make a tool available.

tool is a reference to a tool (or MCP toolset) declared in the request's tools. Under the inline-tools-2026-09-15 beta it may instead be a reference to a tool defined earlier in messages, or a tool_definition object that carries an inline tool definition in definition (the same object a tools entry holds). An mcp_toolset definition also requires the mcp-client-2026-09-15 beta. The tool is offered to the model from this point in the conversation onward.

• type: "tool_addition"

• tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference or BetaToolChangeToolDefinitionParam

• BetaToolChangeToolReference object

Reference to a single tool, by the name the model uses to call it: a tool declared in tools or defined by an earlier tool_addition block. Does not accept the composed {server}_{name} form the server assigns to MCP-resolved tools; use mcp_tool_reference or mcp_toolset_reference for those.

• type: "tool_reference"

• name: string

pattern: ^[a-zA-Z0-9_-]{1,128}$

• BetaToolChangeMCPToolReference object

Reference to a single MCP tool by its server and remote name; the same server_name/name pair mcp_tool_use carries.

• type: "mcp_tool_reference"

• name: string

• server_name: string

• BetaToolChangeMCPToolsetReference object

Reference to every tool in the named MCP server's toolset.

• type: "mcp_toolset_reference"

• server_name: string

• BetaToolChangeToolDefinitionParam object

A tool defined by value: definition is a tools entry (any kind tools accepts, an MCP toolset included). An mcp_toolset given here also requires the mcp-client-2026-09-15 beta.

• type: "tool_definition"

• definition: BetaToolUnion

• BetaTool object

• type: optional "custom" or null

• input_schema: object

JSON schema for this tool's input.

This defines the shape of the input that your tool accepts and that the model will produce.

• type: "object"

• properties: optional map[unknown] or null

• required: optional array of string or null

• name: string

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

minLength: 1, maxLength: 128, pattern: ^[a-zA-Z0-9_-]{1,128}$

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• description: optional string

Description of what this tool does.

Tool descriptions should be as detailed as possible. The more information that the model has about what the tool is and how to use it, the better it will perform. You can use natural language descriptions to reinforce important aspects of the tool input JSON schema.

• eager_input_streaming: optional boolean or null

Enable eager input streaming for this tool. When true, tool input parameters will be streamed incrementally as they are generated, and types will be inferred on-the-fly rather than buffering the full JSON output. When false, streaming is disabled for this tool even if the fine-grained-tool-streaming beta is active. When null (default), uses the default behavior based on beta headers.

• input_examples: optional array of map[unknown]

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaToolBash20241022 object

• type: "bash_20241022"

• name: "bash"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• input_examples: optional array of map[unknown]

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaToolBash20250124 object

• type: "bash_20250124"

• name: "bash"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• input_examples: optional array of map[unknown]

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaCodeExecutionTool20250522 object

• type: "code_execution_20250522"

• name: "code_execution"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaCodeExecutionTool20250825 object

• type: "code_execution_20250825"

• name: "code_execution"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaCodeExecutionTool20260120 object

Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

• type: "code_execution_20260120"

• name: "code_execution"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaCodeExecutionTool20260521 object

Code execution tool with REPL state persistence.

• type: "code_execution_20260521"

• name: "code_execution"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaBrowserToolset20260801 object

The browser toolset: a single tools[] entry (carrying no name) that declares the browser tool family. The model is served the family's tool with any members disabled via configs removed from its schema.

• type: "browser_toolset_20260801"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• configs: optional BetaBrowserToolsetConfigs or null

Sparse per-member overrides, keyed by member name. Absent, null, and {} are equivalent; a member's defaults apply wherever its key is absent.

• type: optional BetaBrowserTypeConfig or null

type's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• close_tab: optional BetaBrowserCloseTabConfig or null

close_tab's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• double_click: optional BetaBrowserDoubleClickConfig or null

double_click's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• file_upload: optional BetaBrowserFileUploadConfig or null

file_upload's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• find: optional BetaBrowserFindConfig or null

find's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• form_input: optional BetaBrowserFormInputConfig or null

form_input's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• get_page_text: optional BetaBrowserGetPageTextConfig or null

get_page_text's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• hold_key: optional BetaBrowserHoldKeyConfig or null

hold_key's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• hover: optional BetaBrowserHoverConfig or null

hover's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• javascript_exec: optional BetaBrowserJavascriptExecConfig or null

javascript_exec's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• key: optional BetaBrowserKeyConfig or null

key's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• left_click: optional BetaBrowserLeftClickConfig or null

left_click's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• left_click_drag: optional BetaBrowserLeftClickDragConfig or null

left_click_drag's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• left_mouse_down: optional BetaBrowserLeftMouseDownConfig or null

left_mouse_down's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• left_mouse_up: optional BetaBrowserLeftMouseUpConfig or null

left_mouse_up's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• list_tabs: optional BetaBrowserListTabsConfig or null

list_tabs's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• middle_click: optional BetaBrowserMiddleClickConfig or null

middle_click's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• mouse_move: optional BetaBrowserMouseMoveConfig or null

mouse_move's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• navigate: optional BetaBrowserNavigateConfig or null

navigate's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• new_tab: optional BetaBrowserNewTabConfig or null

new_tab's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• read_console: optional BetaBrowserReadConsoleConfig or null

read_console's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• read_network: optional BetaBrowserReadNetworkConfig or null

read_network's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• read_page: optional BetaBrowserReadPageConfig or null

read_page's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• right_click: optional BetaBrowserRightClickConfig or null

right_click's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• screenshot: optional BetaBrowserScreenshotConfig or null

screenshot's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• scroll: optional BetaBrowserScrollConfig or null

scroll's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• scroll_to: optional BetaBrowserScrollToConfig or null

scroll_to's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• switch_tab: optional BetaBrowserSwitchTabConfig or null

switch_tab's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• triple_click: optional BetaBrowserTripleClickConfig or null

triple_click's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• wait: optional BetaBrowserWaitConfig or null

wait's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• zoom: optional BetaBrowserZoomConfig or null

zoom's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• BetaToolComputerUse20241022 object

• type: "computer_20241022"

• display_height_px: number

The height of the display in pixels.

minimum: 1

• display_width_px: number

The width of the display in pixels.

minimum: 1

• name: "computer"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• display_number: optional number or null

The X11 display number (e.g. 0, 1) for the display.

minimum: 0

• input_examples: optional array of map[unknown]

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaMemoryTool20250818 object

• type: "memory_20250818"

• name: "memory"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• input_examples: optional array of map[unknown]

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaToolComputerUse20250124 object

• type: "computer_20250124"

• display_height_px: number

The height of the display in pixels.

minimum: 1

• display_width_px: number

The width of the display in pixels.

minimum: 1

• name: "computer"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• display_number: optional number or null

The X11 display number (e.g. 0, 1) for the display.

minimum: 0

• input_examples: optional array of map[unknown]

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaToolTextEditor20241022 object

• type: "text_editor_20241022"

• name: "str_replace_editor"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• input_examples: optional array of map[unknown]

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaToolComputerUse20251124 object

• type: "computer_20251124"

• display_height_px: number

The height of the display in pixels.

minimum: 1

• display_width_px: number

The width of the display in pixels.

minimum: 1

• name: "computer"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• display_number: optional number or null

The X11 display number (e.g. 0, 1) for the display.

minimum: 0

• enable_zoom: optional boolean

Whether to enable an action to take a zoomed-in screenshot of the screen.

• input_examples: optional array of map[unknown]

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaComputerToolset20260801 object

The computer toolset: a single tools[] entry (carrying no name) that declares the computer tool family. The model is served the family's tool with any members disabled via configs removed from its schema. Every member is enabled by default, zoom included. The single-tool options display_number and enable_zoom are not fields of a toolset entry — it carries only type, configs, and cache_control; zoom is controlled via configs.zoom.enabled.

• type: "computer_toolset_20260801"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• configs: optional BetaComputerToolsetConfigs or null

Sparse per-member overrides, keyed by member name. Absent, null, and {} are equivalent; a member's defaults apply wherever its key is absent.

• type: optional BetaComputerTypeConfig or null

type's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• cursor_position: optional BetaComputerCursorPositionConfig or null

cursor_position's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• double_click: optional BetaComputerDoubleClickConfig or null

double_click's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• hold_key: optional BetaComputerHoldKeyConfig or null

hold_key's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• key: optional BetaComputerKeyConfig or null

key's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• left_click: optional BetaComputerLeftClickConfig or null

left_click's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• left_click_drag: optional BetaComputerLeftClickDragConfig or null

left_click_drag's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• left_mouse_down: optional BetaComputerLeftMouseDownConfig or null

left_mouse_down's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• left_mouse_up: optional BetaComputerLeftMouseUpConfig or null

left_mouse_up's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• middle_click: optional BetaComputerMiddleClickConfig or null

middle_click's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• mouse_move: optional BetaComputerMouseMoveConfig or null

mouse_move's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• right_click: optional BetaComputerRightClickConfig or null

right_click's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• screenshot: optional BetaComputerScreenshotConfig or null

screenshot's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• scroll: optional BetaComputerScrollConfig or null

scroll's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• triple_click: optional BetaComputerTripleClickConfig or null

triple_click's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• wait: optional BetaComputerWaitConfig or null

wait's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• zoom: optional BetaComputerZoomConfig or null

zoom's config overrides.

• defer_loading: optional boolean or null

Defer loading for this member. Must resolve to the same value on every enabled member of the toolset.

• enabled: optional boolean or null

Whether this member is offered to the model. Default is per member, per the toolset's documentation. A member whose enabled resolves false is withheld from the served schema.

• BetaToolTextEditor20250124 object

• type: "text_editor_20250124"

• name: "str_replace_editor"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• input_examples: optional array of map[unknown]

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaToolTextEditor20250429 object

• type: "text_editor_20250429"

• name: "str_replace_based_edit_tool"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• input_examples: optional array of map[unknown]

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaToolTextEditor20250728 object

• type: "text_editor_20250728"

• name: "str_replace_based_edit_tool"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• input_examples: optional array of map[unknown]

• max_characters: optional number or null

Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.

minimum: 1

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaWebSearchTool20250305 object

• type: "web_search_20250305"

• name: "web_search"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• allowed_domains: optional array of string or null

If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

• blocked_domains: optional array of string or null

If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• max_uses: optional number or null

Maximum number of times the tool can be used in the API request.

minimum: 1

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• user_location: optional BetaUserLocation or null

Parameters for the user's location. Used to provide more relevant search results.

• type: "approximate"

• city: optional string or null

The city of the user.

minLength: 1, maxLength: 255

• country: optional string or null

The two letter ISO country code of the user.

minLength: 2, maxLength: 2

• region: optional string or null

The region of the user.

minLength: 1, maxLength: 255

• timezone: optional string or null

The IANA timezone of the user.

minLength: 1, maxLength: 255

• BetaWebFetchTool20250910 object

• type: "web_fetch_20250910"

• name: "web_fetch"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• allowed_domains: optional array of string or null

List of domains to allow fetching from

• blocked_domains: optional array of string or null

List of domains to block fetching from

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• citations: optional BetaCitationsConfigParam or null

Citations configuration for fetched documents. Citations are disabled by default.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• max_content_tokens: optional number or null

Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

minimum: 1

• max_uses: optional number or null

Maximum number of times the tool can be used in the API request.

minimum: 1

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• url_sources: optional BetaWebFetchURLSources or null

Which sources contribute to the set of URLs the tool may fetch. Omitted means every source.

• client_tool_results: optional BetaWebFetchURLSourceAll or BetaWebFetchURLSourceNone or BetaWebFetchURLSourceOnly or BetaWebFetchURLSourceExcept

Which client tools' results contribute fetchable URLs: "all", "none", or an only or except list of client tool names from tools[].

• BetaWebFetchURLSourceAll object

The url_sources variant under which a source contributes in full: every result of the tool filter's source, or all user input.

• type: "all"

• BetaWebFetchURLSourceNone object

The url_sources variant under which a source contributes nothing: no result of the tool filter's source, or no user input.

• type: "none"

• BetaWebFetchURLSourceOnly object

The tool filter variant under which only the named tools' results contribute.

• type: "only"

• tools: array of BetaWebFetchURLSourceToolReference

• type: "tool_reference"

• name: string

• BetaWebFetchURLSourceExcept object

The tool filter variant under which every result but the named tools' contributes.

• type: "except"

• tools: array of BetaWebFetchURLSourceToolReference

• type: "tool_reference"

• name: string

• server_tool_results: optional BetaWebFetchURLSourceAll or BetaWebFetchURLSourceNone or BetaWebFetchURLSourceOnly or BetaWebFetchURLSourceExcept

Which server tools' results contribute fetchable URLs: "all", "none", or an only or except list of server tool names from tools[]; only web_search and web_fetch results ever contribute.

• BetaWebFetchURLSourceAll object

The url_sources variant under which a source contributes in full: every result of the tool filter's source, or all user input.

• BetaWebFetchURLSourceNone object

The url_sources variant under which a source contributes nothing: no result of the tool filter's source, or no user input.

• BetaWebFetchURLSourceOnly object

The tool filter variant under which only the named tools' results contribute.

• BetaWebFetchURLSourceExcept object

The tool filter variant under which every result but the named tools' contributes.

• user_input: optional BetaWebFetchURLSourceAll or BetaWebFetchURLSourceNone

Whether URLs in user messages are fetchable: "all" or "none".

• BetaWebFetchURLSourceAll object

The url_sources variant under which a source contributes in full: every result of the tool filter's source, or all user input.

• BetaWebFetchURLSourceNone object

The url_sources variant under which a source contributes nothing: no result of the tool filter's source, or no user input.

• BetaWebSearchTool20260209 object

• type: "web_search_20260209"

• name: "web_search"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• allowed_domains: optional array of string or null

If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

• blocked_domains: optional array of string or null

If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• max_uses: optional number or null

Maximum number of times the tool can be used in the API request.

minimum: 1

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• user_location: optional BetaUserLocation or null

Parameters for the user's location. Used to provide more relevant search results.

• BetaWebFetchTool20260209 object

• type: "web_fetch_20260209"

• name: "web_fetch"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• allowed_domains: optional array of string or null

List of domains to allow fetching from

• blocked_domains: optional array of string or null

List of domains to block fetching from

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• citations: optional BetaCitationsConfigParam or null

Citations configuration for fetched documents. Citations are disabled by default.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• max_content_tokens: optional number or null

Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

minimum: 1

• max_uses: optional number or null

Maximum number of times the tool can be used in the API request.

minimum: 1

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• url_sources: optional BetaWebFetchURLSources or null

Which sources contribute to the set of URLs the tool may fetch. Omitted means every source.

• BetaWebFetchTool20260309 object

Web fetch tool with use_cache parameter for bypassing cached content.

• type: "web_fetch_20260309"

• name: "web_fetch"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• allowed_domains: optional array of string or null

List of domains to allow fetching from

• blocked_domains: optional array of string or null

List of domains to block fetching from

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• citations: optional BetaCitationsConfigParam or null

Citations configuration for fetched documents. Citations are disabled by default.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• max_content_tokens: optional number or null

Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

minimum: 1

• max_uses: optional number or null

Maximum number of times the tool can be used in the API request.

minimum: 1

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• url_sources: optional BetaWebFetchURLSources or null

Which sources contribute to the set of URLs the tool may fetch. Omitted means every source.

• use_cache: optional boolean

Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

• BetaWebSearchTool20260318 object

• type: "web_search_20260318"

• name: "web_search"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• allowed_domains: optional array of string or null

If provided, only these domains will be included in results. Cannot be used alongside blocked_domains.

• blocked_domains: optional array of string or null

If provided, these domains will never appear in results. Cannot be used alongside allowed_domains.

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• max_uses: optional number or null

Maximum number of times the tool can be used in the API request.

minimum: 1

• response_inclusion: optional "full" or "excluded"

How this tool's result blocks appear in the API response when the result was consumed by a completed code_execution call in the same turn. 'full' returns the complete content (default). 'excluded' drops the nested server_tool_use and result block pair entirely. Results from direct calls, or from code_execution calls that paused before completing, are always returned in full so they can be sent back on the next turn.

• "full"

• "excluded"

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• user_location: optional BetaUserLocation or null

Parameters for the user's location. Used to provide more relevant search results.

• BetaWebFetchTool20260318 object

• type: "web_fetch_20260318"

• name: "web_fetch"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• allowed_domains: optional array of string or null

List of domains to allow fetching from

• blocked_domains: optional array of string or null

List of domains to block fetching from

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• citations: optional BetaCitationsConfigParam or null

Citations configuration for fetched documents. Citations are disabled by default.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• max_content_tokens: optional number or null

Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

minimum: 1

• max_uses: optional number or null

Maximum number of times the tool can be used in the API request.

minimum: 1

• response_inclusion: optional "full" or "excluded"

How this tool's result blocks appear in the API response when the result was consumed by a completed code_execution call in the same turn. 'full' returns the complete content (default). 'excluded' drops the nested server_tool_use and result block pair entirely. Results from direct calls, or from code_execution calls that paused before completing, are always returned in full so they can be sent back on the next turn.

• "full"

• "excluded"

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• url_sources: optional BetaWebFetchURLSources or null

Which sources contribute to the set of URLs the tool may fetch. Omitted means every source.

• use_cache: optional boolean

Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

• BetaAdvisorTool20260301 object

• type: "advisor_20260301"

• model: Model

The model that will complete your prompt.

See models for additional details and options.

• string

• "haijun-fable-5-1" or "haijun-opus-5-5" or "haijun-mythos-5-1" or 15 more

The model that will complete your prompt.

See models for additional details and options.

• "haijun-fable-5-1"

Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

• "haijun-opus-5-5"

Powerful intelligence for coding, knowledge work, and long-running agents

• "haijun-mythos-5-1"

Our most capable model for cybersecurity and biology research, available through trusted access programs

• "haijun-sonnet-5"

High-performance model for coding and agents

• "haijun-fable-5"

Next generation of intelligence for the hardest knowledge work and coding problems

• "haijun-mythos-5"

Most capable model for cybersecurity and biology research

• "haijun-opus-5"

Powerful intelligence for long-running agents and coding

• "haijun-opus-4-8"

Powerful intelligence for long-running agents and coding

• "haijun-opus-4-7"

Powerful intelligence for long-running agents and coding

• "haijun-opus-4-6"

Powerful intelligence for long-running agents and coding

• "haijun-sonnet-4-6"

Best combination of speed and intelligence

• "haijun-haiku-4-5"

Fastest model with near-frontier intelligence

• "haijun-haiku-4-5-20251001"

Fastest model with near-frontier intelligence

• "haijun-opus-4-5"

Powerful intelligence for long-running agents and coding

• "haijun-opus-4-5-20251101"

Powerful intelligence for long-running agents and coding

• "haijun-sonnet-4-5"

High-performance model for agents and coding

• "haijun-sonnet-4-5-20250929"

High-performance model for agents and coding

• "haijun-mythos-preview"

Deprecated: Will reach end-of-life on June 30, 2026. Please migrate to haijun-mythos-5. Visit https://raw.haijun.my.id/docs/ for more information.

New class of intelligence, strongest in coding and cybersecurity

• name: "advisor"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• caching: optional BetaCacheControlEphemeral or null

Caching for the advisor's own prompt. When set, each advisor call writes a cache entry at the given TTL so subsequent calls in the same conversation read the stable prefix. When omitted, the advisor prompt is not cached.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• max_tokens: optional number or null

Bounds the advisor's total output (thinking + text) per call. When the advisor hits this cap, the returned advisor_result or advisor_redacted_result block carries stop_reason='max_tokens', and a truncation note is appended to the advice text the worker model sees (inside the encrypted blob in redacted mode). When set, the server also emits a remaining-tokens budget block in the advisor's prompt so the advisor self-shapes toward the cap. When omitted, the advisor model's default output cap applies and no budget block is emitted.

minimum: 1024

• max_uses: optional number or null

Maximum number of times the tool can be used in the API request.

minimum: 1

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaToolSearchToolBm25_20251119 object

• type: "tool_search_tool_bm25_20251119" or "tool_search_tool_bm25"

• "tool_search_tool_bm25_20251119"

• "tool_search_tool_bm25"

• name: "tool_search_tool_bm25"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaToolSearchToolRegex20251119 object

• type: "tool_search_tool_regex_20251119" or "tool_search_tool_regex"

• "tool_search_tool_regex_20251119"

• "tool_search_tool_regex"

• name: "tool_search_tool_regex"

Name of the tool.

This is how the tool will be called by the model and in tool_use blocks.

• allowed_callers: optional array of "direct" or "code_execution_20250825" or "code_execution_20260120" or "code_execution_20260521"

• "direct"

• "code_execution_20250825"

• "code_execution_20260120"

• "code_execution_20260521"

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• defer_loading: optional boolean

If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

• strict: optional boolean

When true, guarantees schema validation on tool names and inputs

• BetaMCPToolset object

Configuration for a group of tools from an MCP server.

Allows configuring enabled status and defer_loading for all tools from an MCP server, with optional per-tool overrides.

• type: "mcp_toolset"

• mcp_server_name: string

Name of the MCP server to configure tools for

minLength: 1, maxLength: 255

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• configs: optional map[BetaMCPToolConfig] or null

Configuration overrides for specific tools, keyed by tool name

• defer_loading: optional boolean

• enabled: optional boolean

• default_config: optional BetaMCPToolDefaultConfig

Default configuration applied to all tools from this server

• defer_loading: optional boolean

• enabled: optional boolean

• tools: optional array of BetaMCPToolParam or null

The server's tool listing, pinned: when present, the server is not asked for its tools before sampling and exactly these entries, with default_config and configs applied, are the toolset's tools. Copy it from the mcp_tool_listing block of an earlier response.

• input_schema: map[unknown]

The tool's input schema as the MCP server lists it, verbatim.

• name: string

The tool's name as the MCP server lists it (not prefixed with the server name).

minLength: 1

• description: optional string or null

The tool's description as the MCP server lists it.

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• BetaRequestToolRemovalBlock object

Mid-conversation directive to withdraw a tool.

tool references a tool (or MCP toolset) by name: one declared in the request's tools or defined earlier in messages. It is no longer offered to the model from this point in the conversation onward.

• type: "tool_removal"

• tool: BetaToolChangeToolReference or BetaToolChangeMCPToolReference or BetaToolChangeMCPToolsetReference

• BetaToolChangeToolReference object

Reference to a single tool, by the name the model uses to call it: a tool declared in tools or defined by an earlier tool_addition block. Does not accept the composed {server}_{name} form the server assigns to MCP-resolved tools; use mcp_tool_reference or mcp_toolset_reference for those.

• BetaToolChangeMCPToolReference object

Reference to a single MCP tool by its server and remote name; the same server_name/name pair mcp_tool_use carries.

• BetaToolChangeMCPToolsetReference object

Reference to every tool in the named MCP server's toolset.

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• BetaRequestToolAdditionBlock object

Mid-conversation directive to make a tool available.

tool is a reference to a tool (or MCP toolset) declared in the request's tools. Under the inline-tools-2026-09-15 beta it may instead be a reference to a tool defined earlier in messages, or a tool_definition object that carries an inline tool definition in definition (the same object a tools entry holds). An mcp_toolset definition also requires the mcp-client-2026-09-15 beta. The tool is offered to the model from this point in the conversation onward.

• BetaRequestToolRemovalBlock object

Mid-conversation directive to withdraw a tool.

tool references a tool (or MCP toolset) by name: one declared in the request's tools or defined earlier in messages. It is no longer offered to the model from this point in the conversation onward.

• BetaMCPToolListingBlockParam object

The tool listing an MCP server returned while an earlier response was produced, as that response carried it. Send the assistant message back unchanged, this block included, and the server uses this listing for the matching mcp_toolset instead of asking the MCP server again.

• type: "mcp_tool_listing"

• mcp_server_name: string

The name of the MCP server this listing came from, as mcp_servers declares it.

minLength: 1, maxLength: 255

• tools: array of BetaMCPToolParam

The server's tools, exactly as the response listed them.

• input_schema: map[unknown]

The tool's input schema as the MCP server lists it, verbatim.

• name: string

The tool's name as the MCP server lists it (not prefixed with the server name).

minLength: 1

• description: optional string or null

The tool's description as the MCP server lists it.

• BetaFallbackBlockParam object

A fallback block echoed back from a prior response.

Accepted in messages[].content and not rendered into the prompt; not validated against the request's fallbacks chain or top-level model.

Echo the assistant turn back verbatim, including this block in its original position. The block marks the boundary between content produced before and after a fallback hop, and the server relies on that boundary to validate the turn: when thinking runs flank the boundary, omitting the block merges them into one span the server cannot validate (the request is rejected), and moving it into the middle of a single run is likewise rejected; between non-thinking blocks the block's placement has no validation effect.

• type: "fallback"

• from: BetaFallbackInfoParam

Identifies one hop of a fallback transition.

• model: Model

The model that will complete your prompt.

See models for additional details and options.

• to: BetaFallbackInfoParam

Identifies one hop of a fallback transition.

• trigger: optional unknown

The response block's trigger, echoed verbatim. Accepted and ignored by the server; any object or null is allowed.

• role: "user" or "assistant" or "system"

• "user"

• "assistant"

• "system"

• clear_at: optional "next_user_message" or "never" or null

How long this system message's text stays in front of the model. "never" (the default) renders it on every request that includes it. "next_user_message" renders it only for the user turn it follows: once a later role: "user" message exists in messages the message stays in the array (send it unchanged) but is no longer shown to the model. Only permitted on role: "system" messages.

• "next_user_message"

• "never"

• output_config: optional BetaSystemMessageOutputConfig or null

Per-message output configuration on a role:"system" input message.

Fields here apply per-turn; format remains top-level only. An empty {} is accepted on a message that carries content; a message with neither content nor output_config fields is rejected.

• effort: optional "low" or "medium" or "high" or 2 more or null

How much effort the model should put into its response. Higher effort levels may result in more thorough analysis but take longer.

Valid values are low, medium, high, xhigh, or max.

• "low"

• "medium"

• "high"

• "xhigh"

• "max"

• model: Model

The model that will complete your prompt.

See models for additional details and options.

• cache_control: optional BetaCacheControlEphemeral or null

Top-level cache control automatically applies a cache_control marker to the last cacheable block in the request.

• compaction: optional BetaCompactionConfig or null

Compaction configuration.

When set on POST /v1/messages, the request is a compaction request: the conversation in messages is summarized and the response holds only the resulting compaction block (stop_reason "compaction"), which later requests send first in messages in place of the messages it summarizes. POST /v1/messages/count_tokens accepts this parameter and ignores it: the count it returns is for the conversation in messages as sent. Cannot be combined with context_management.

• type: "summarize"

• instructions: optional string or null

Replaces the server's default summarization prompt for this request. An empty or whitespace-only value counts as absent.

maxLength: 16384

• context_management: optional BetaContextManagementConfig or null

Context management configuration.

This allows you to control how Haijun manages context across multiple requests, such as whether to clear function results or not.

• edits: optional array of BetaClearToolUses20250919Edit or BetaClearThinking20251015Edit or BetaCompact20260112Edit

List of context management edits to apply

• BetaClearToolUses20250919Edit object

• type: "clear_tool_uses_20250919"

• clear_at_least: optional BetaInputTokensClearAtLeast or null

Minimum number of tokens that must be cleared when triggered. Context will only be modified if at least this many tokens can be removed.

• type: "input_tokens"

• value: number

minimum: 0

• clear_tool_inputs: optional boolean or array of string or null

Whether to clear all tool inputs (bool) or specific tool inputs to clear (list)

• boolean

• array of string

• exclude_tools: optional array of string or null

Tool names whose uses are preserved from clearing

• keep: optional BetaToolUsesKeep

Number of tool uses to retain in the conversation

• type: "tool_uses"

• value: number

minimum: 0

• trigger: optional BetaInputTokensTrigger or BetaToolUsesTrigger

Condition that triggers the context management strategy

• BetaInputTokensTrigger object

• type: "input_tokens"

• value: number

minimum: 1

• BetaToolUsesTrigger object

• type: "tool_uses"

• value: number

minimum: 1

• BetaClearThinking20251015Edit object

• type: "clear_thinking_20251015"

• keep: optional BetaThinkingTurns or BetaAllThinkingTurns or "all"

Number of most recent assistant turns to keep thinking blocks for. Older turns will have their thinking blocks removed.

• BetaThinkingTurns object

• type: "thinking_turns"

• value: number

minimum: 1

• BetaAllThinkingTurns object

• type: "all"

• "all"

• BetaCompact20260112Edit object

Automatically compact older context when reaching the configured trigger threshold.

• type: "compact_20260112"

• instructions: optional string or null

Additional instructions for summarization.

• pause_after_compaction: optional boolean

Whether to pause after compaction and return the compaction block to the user.

• trigger: optional BetaInputTokensTrigger or null

When to trigger compaction. Defaults to 150000 input tokens.

• mcp_servers: optional array of BetaRequestMCPServerURLDefinition

MCP servers to be utilized in this request

maxItems: 20

• type: "url"

• name: string

• url: string

• authorization_token: optional string or null

• tool_configuration: optional BetaRequestMCPServerToolConfiguration or null

• allowed_tools: optional array of string or null

• enabled: optional boolean or null

• output_config: optional BetaOutputConfig

Configuration options for the model's output, such as the output format.

• effort: optional "low" or "medium" or "high" or 2 more or null

How much effort the model should put into its response. Higher effort levels may result in more thorough analysis but take longer.

Valid values are low, medium, high, xhigh, or max.

• "low"

• "medium"

• "high"

• "xhigh"

• "max"

• format: optional BetaJSONOutputFormat or null

A schema to specify Haijun's output format in responses. See structured outputs

• type: "json_schema"

• schema: map[unknown]

The JSON schema of the format

• task_budget: optional BetaTokenTaskBudget or null

Configuration for token budget tracking across contexts.

• type: "tokens"

The budget type. Currently only 'tokens' is supported.

• total: number

Total token budget across all contexts in the session.

minimum: 1024

• remaining: optional number or null

Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

minimum: 0

• speed: optional "standard" or "fast" or null

The inference speed mode for this request. "fast" enables high output-tokens-per-second inference.

• "standard"

• "fast"

• system: optional string or array of BetaTextBlockParam

System prompt.

A system prompt is a way of providing context and instructions to Haijun, such as specifying a particular goal or role. See our guide to system prompts.

• string

• array of BetaTextBlockParam

• type: "text"

• text: string

minLength: 1

• cache_control: optional BetaCacheControlEphemeral or null

Create a cache control breakpoint at this content block.

• citations: optional array of BetaTextCitationParam or null

• thinking: optional BetaThinkingConfigParam

Configuration for enabling Haijun's extended thinking.

When enabled, responses include thinking content blocks showing Haijun's thinking process before the final answer. Requires a minimum budget of 1,024 tokens and counts towards your max_tokens limit.

See extended thinking for details.

• BetaThinkingConfigEnabled object

• type: "enabled"

• budget_tokens: number

Determines how many tokens Haijun can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

Must be ≥1024 and less than max_tokens.

See extended thinking for details.

minimum: 1024

• block_binding: optional BetaThinkingBlockBinding or null

Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. null, absent or an empty object means every default.

• prefix_mismatch_behavior: optional BetaThinkingPrefixMismatchBehavior or null

"error" (default) | "drop_block". What happens when a thinking block in messages fails the conversation check (it was created in a different conversation, or the messages before it have changed since). "error" fails the request with a 400 error. "drop_block" removes the failing blocks and the request proceeds; each removal is reported in input_transformations.

• "error"

• "drop_block"

• display: optional "summarized" or "omitted" or "updates" or null

Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

• "summarized"

• "omitted"

• "updates"

• BetaThinkingConfigDisabled object

• type: "disabled"

• BetaThinkingConfigAdaptive object

• type: "adaptive"

• block_binding: optional BetaThinkingBlockBinding or null

Controls for block binding: what happens when a thinking block this request sends back fails the conversation check. null, absent or an empty object means every default.

• display: optional "summarized" or "omitted" or "updates" or null

Controls how thinking content appears in the response. When set to summarized, thinking is returned normally. When set to omitted, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to summarized.

• "summarized"

• "omitted"

• "updates"

• tool_choice: optional BetaToolChoice

How the model should use the provided tools. The model can use a specific tool, any available tool, decide by itself, or not use tools at all.

• BetaToolChoiceAuto object

The model will automatically decide whether to use tools.

• type: "auto"

• disable_parallel_tool_use: optional boolean

Whether to disable parallel tool use.

Defaults to false. If set to true, the model will output at most one tool use.

• BetaToolChoiceAny object

The model will use any available tools.

• type: "any"

• disable_parallel_tool_use: optional boolean

Whether to disable parallel tool use.

Defaults to false. If set to true, the model will output exactly one tool use.

• BetaToolChoiceTool object

The model will use the specified tool with tool_choice.name.

• type: "tool"

• name: string

The name of the tool to use.

• disable_parallel_tool_use: optional boolean

Whether to disable parallel tool use.

Defaults to false. If set to true, the model will output exactly one tool use.

• BetaToolChoiceNone object

The model will not be allowed to use tools.

• type: "none"

• tools: optional array of BetaTool or BetaToolBash20241022 or BetaToolBash20250124 or 25 more

Definitions of tools that the model may use.

If you include tools in your API request, the model may return tool_use content blocks that represent the model's use of those tools. You can then run those tools using the tool input generated by the model and then optionally return results back to the model using tool_result content blocks.

There are two types of tools: client tools and server tools. The behavior described below applies to client tools. For server tools, see their individual documentation as each has its own behavior (e.g., the web search tool).

Each tool definition includes:

• name: Name of the tool.
• description: Optional, but strongly-recommended description of the tool.
• input_schema: JSON schema for the tool input shape that the model will produce in tool_use output content blocks.

For example, if you defined tools as:

  [
    {
      "name": "get_stock_price",
      "description": "Get the current stock price for a given ticker symbol.",
      "input_schema": {
        "type": "object",
        "properties": {
          "ticker": {
            "type": "string",
            "description": "The stock ticker symbol, e.g. AAPL for Apple Inc."
          }
        },
        "required": ["ticker"]
      }
    }
  ]

And then asked the model "What's the S&P 500 at today?", the model might produce tool_use content blocks in the response like this:

  [
    {
      "type": "tool_use",
      "id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
      "name": "get_stock_price",
      "input": { "ticker": "^GSPC" }
    }
  ]

You might then run your get_stock_price tool with {"ticker": "^GSPC"} as an input, and return the following back to the model in a subsequent user message:

  [
    {
      "type": "tool_result",
      "tool_use_id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
      "content": "259.75 USD"
    }
  ]

Tools can be used for workflows that include running client-side tools and functions, or more generally whenever you want the model to produce a particular JSON structure of output.

See our guide for more details.

• BetaTool object

• BetaToolBash20241022 object

• BetaToolBash20250124 object

• BetaCodeExecutionTool20250522 object

• BetaCodeExecutionTool20250825 object

• BetaCodeExecutionTool20260120 object

Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

• BetaCodeExecutionTool20260521 object

Code execution tool with REPL state persistence.

• BetaBrowserToolset20260801 object

The browser toolset: a single tools[] entry (carrying no name) that declares the browser tool family. The model is served the family's tool with any members disabled via configs removed from its schema.

• BetaToolComputerUse20241022 object

• BetaMemoryTool20250818 object

• BetaToolComputerUse20250124 object

• BetaToolTextEditor20241022 object

• BetaToolComputerUse20251124 object

• BetaComputerToolset20260801 object

The computer toolset: a single tools[] entry (carrying no name) that declares the computer tool family. The model is served the family's tool with any members disabled via configs removed from its schema. Every member is enabled by default, zoom included. The single-tool options display_number and enable_zoom are not fields of a toolset entry — it carries only type, configs, and cache_control; zoom is controlled via configs.zoom.enabled.

• BetaToolTextEditor20250124 object

• BetaToolTextEditor20250429 object

• BetaToolTextEditor20250728 object

• BetaWebSearchTool20250305 object

• BetaWebFetchTool20250910 object

• BetaWebSearchTool20260209 object

• BetaWebFetchTool20260209 object

• BetaWebFetchTool20260309 object

Web fetch tool with use_cache parameter for bypassing cached content.

• BetaWebSearchTool20260318 object

• BetaWebFetchTool20260318 object

• BetaAdvisorTool20260301 object

• BetaToolSearchToolBm25_20251119 object

• BetaToolSearchToolRegex20251119 object

• BetaMCPToolset object

Configuration for a group of tools from an MCP server.

Allows configuring enabled status and defer_loading for all tools from an MCP server, with optional per-tool overrides.

• output_format: optional BetaJSONOutputFormat or null

Deprecated

Deprecated: Use output_config.format instead. See structured outputs

A schema to specify Haijun's output format in responses. This parameter will be removed in a future release.

#Returns

• BetaMessageTokensCount object

• context_management: BetaCountTokensContextManagementResponse or null

Information about context management applied to the message.

• original_input_tokens: number

The original token count before context management was applied

• input_tokens: number

The total number of tokens across the provided list of messages, system prompt, and tools.

#Example

curl https://haijun.my.id/v1/messages/count_tokens \
    -H 'Content-Type: application/json' \
    -H 'juglow-version: 2023-06-01' \
    -H "X-Api-Key: $JUGLOW_API_KEY" \
    -d '{
          "messages": [
            {
              "content": "Hello, world",
              "role": "user"
            }
          ],
          "model": "haijun-opus-5",
          "system": [
            {
              "text": "Today'\''s date is 2024-06-01.",
              "type": "text"
            }
          ],
          "thinking": {
            "type": "adaptive"
          },
          "tools": [
            {
              "input_schema": {
                "type": "object",
                "properties": {
                  "location": "bar",
                  "unit": "bar"
                },
                "required": [
                  "location"
                ]
              },
              "name": "name"
            }
          ]
        }'

#Response (200)

{
  "context_management": {
    "original_input_tokens": 0
  },
  "input_tokens": 2095
}