Anthropic Token Counting API

openapi: 3.1.0
info:
  title: Anthropic Admin Agents Token Counting API
  description: Manage administrative functions for Anthropic organizations, workspaces, users, invites, and API keys.
  version: 1.0.0
  contact:
    name: Anthropic
    url: https://www.anthropic.com
    email: support@anthropic.com
  license:
    name: Anthropic API License
    url: https://www.anthropic.com/terms
servers:
- url: https://api.anthropic.com/v1
  description: Production Server
security:
- AdminApiKeyAuth: []
tags:
- name: Token Counting
  description: Count tokens before sending a Message request
paths:
  /v1/messages/count_tokens:
    post:
      summary: Anthropic Count Message Tokens
      description: 'Count tokens for a prospective Message request, including any tools, images, and documents. Returns the input token total without creating the message or charging output tokens.

        '
      operationId: countMessageTokens
      tags:
      - Token Counting
      parameters:
      - $ref: '#/components/parameters/AnthropicVersion'
      - $ref: '#/components/parameters/AnthropicBeta'
      - $ref: '#/components/parameters/ApiKey'
      - $ref: '#/components/parameters/ContentType'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CountTokensRequest'
            examples:
              SimpleCount:
                $ref: '#/components/examples/SimpleCountTokensExample'
      responses:
        '200':
          description: Token count returned successfully.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CountTokensResponse'
              examples:
                Default:
                  $ref: '#/components/examples/CountTokensResponseExample'
        4XX:
          $ref: '#/components/responses/ErrorResponse'
components:
  examples:
    CountTokensResponseExample:
      summary: Token count response
      value:
        input_tokens: 9
    SimpleCountTokensExample:
      summary: Simple token count
      value:
        model: claude-opus-4-7
        messages:
        - role: user
          content: How many tokens is this prompt?
  responses:
    ErrorResponse:
      description: Error response.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  parameters:
    AnthropicVersion:
      name: anthropic-version
      in: header
      required: true
      description: API version date.
      schema:
        type: string
        default: '2023-06-01'
    ApiKey:
      name: x-api-key
      in: header
      required: true
      description: Anthropic API key.
      schema:
        type: string
    AnthropicBeta:
      name: anthropic-beta
      in: header
      required: false
      description: Comma-separated beta feature headers.
      schema:
        type: string
    ContentType:
      name: content-type
      in: header
      required: true
      description: Must be application/json.
      schema:
        type: string
        default: application/json
  schemas:
    CountTokensResponse:
      type: object
      properties:
        input_tokens:
          type: integer
          description: Total input tokens for the prospective request.
          example: 2095
    CountTokensRequest:
      type: object
      required:
      - model
      - messages
      properties:
        model:
          type: string
          description: Claude model ID (for example, claude-opus-4-7).
          example: claude-opus-4-7
        messages:
          type: array
          description: Ordered conversation messages.
          items:
            type: object
            properties:
              role:
                type: string
                enum:
                - user
                - assistant
              content:
                oneOf:
                - type: string
                - type: array
                  items:
                    type: object
        system:
          oneOf:
          - type: string
          - type: array
            items:
              type: object
          description: Optional system prompt(s).
        tools:
          type: array
          description: Tool definitions to include in the count.
          items:
            type: object
    Error:
      type: object
      properties:
        type:
          type: string
        error:
          type: object
          properties:
            type:
              type: string
            message:
              type: string
  securitySchemes:
    AdminApiKeyAuth:
      type: apiKey
      in: header
      name: x-api-key
      description: Your Admin API key for authentication (starts with sk-ant-admin...).