> ## Documentation Index > Fetch the complete documentation index at: https://docs.aixy-gateway.com/llms.txt > Use this file to discover all available pages before exploring further. # Count Anthropic message tokens > Count the input tokens for a native Anthropic Messages request without creating a model response. The model uses the same project-scoped provider credential and access policy as `/v1/messages`. Native token-count support is required for the selected provider and model; Aixy does not synthesize it from translated conversation support. ## OpenAPI ````yaml /openapi.json post /v1/messages/count_tokens openapi: 3.1.0 info: title: Aixy Inference API version: 0.1.0 description: >- Route requests to configured AI providers through OpenAI- and Anthropic-compatible APIs. Aixy applies project access, model policies, guardrails, routing, budgets, and usage attribution before forwarding inference traffic. Create connections, API keys and policies in the Aixy dashboard. The management API is a dashboard service and is not a public integration contract. Native provider features depend on the selected model and connection; translated requests support the documented conversation and function-tool subset. Unsupported combinations return explicit errors. Examples use illustrative model IDs; select an ID available to your project. servers: - url: https://api.aixy-gateway.com description: Aixy production gateway security: [] tags: - name: OpenAI description: OpenAI-compatible conversations, function tools and incremental streams. - name: Anthropic description: Anthropic-compatible messages and provider-native input token counting. - name: Decisions description: Typed, non-streaming classification and scoring inference. - name: Models description: Discover the models available to your project API key. paths: /v1/messages/count_tokens: post: tags: - Anthropic summary: Count Anthropic message tokens description: >- Count the input tokens for a native Anthropic Messages request without creating a model response. The model uses the same project-scoped provider credential and access policy as `/v1/messages`. Native token-count support is required for the selected provider and model; Aixy does not synthesize it from translated conversation support. operationId: count_message_tokens parameters: - $ref: '#/components/parameters/XRequestId' - $ref: '#/components/parameters/XAixyClient' - $ref: '#/components/parameters/XAixySession' - $ref: '#/components/parameters/XAixySessionId' - $ref: '#/components/parameters/AnthropicVersion' - $ref: '#/components/parameters/AnthropicBeta' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/AnthropicTokenCountRequest' examples: basic: summary: Basic request value: model: anthropic/claude-sonnet-4-5 messages: - role: user content: Explain this code. functionTools: summary: Function tools (executed by your application) value: model: anthropic/claude-sonnet-4-5 messages: - role: user content: What is the weather in Paris? tools: - name: get_weather description: Read the weather for a city. input_schema: type: object properties: city: type: string required: - city additionalProperties: false responses: '200': description: Successful Anthropic response. headers: x-request-id: description: >- Aixy request identifier for correlation with Activity and support. schema: type: string example: req_example_01 content: application/json: schema: $ref: '#/components/schemas/AnthropicTokenCount' example: input_tokens: 8 '400': $ref: '#/components/responses/AnthropicError' '401': $ref: '#/components/responses/AnthropicError' '403': $ref: '#/components/responses/AnthropicError' '404': $ref: '#/components/responses/AnthropicError' '408': $ref: '#/components/responses/AnthropicError' '413': $ref: '#/components/responses/AnthropicError' '424': $ref: '#/components/responses/AnthropicError' '429': $ref: '#/components/responses/AnthropicRateLimitError' '500': $ref: '#/components/responses/InferenceInternalError' '502': $ref: '#/components/responses/AnthropicError' '503': $ref: '#/components/responses/AnthropicError' '504': $ref: '#/components/responses/AnthropicError' default: $ref: '#/components/responses/NativeProviderError' security: - GatewayApiKey: [] - AnthropicApiKey: [] components: parameters: XRequestId: name: X-Request-ID in: header required: false description: Optional caller-generated request identifier for end-to-end tracing. schema: type: string maxLength: 255 XAixyClient: name: X-Aixy-Client in: header required: false description: >- Optional application[/version] for Activity attribution. Overrides User-Agent detection. Use a product name, not personal data or credentials. Names are 1-64 ASCII letters, digits, spaces, dots, underscores or hyphens, starting with a letter or digit. Optional versions start with a digit and use up to 32 letters, digits, dots, underscores, plus signs or hyphens. Invalid values are ignored. This self-declared label grants no permissions and is not forwarded. schema: type: string maxLength: 97 example: Acme Support/1.2.3 XAixySession: name: X-Aixy-Session in: header required: false description: >- Optional opaque session identifier for virtual routes with session affinity. Scoped to the authenticated caller and alias; never forwarded or recorded. Send full conversation history. Invalid values return 400 when affinity is enabled. Omission retains the route's normal strategy. schema: type: string minLength: 1 maxLength: 128 pattern: ^[A-Za-z0-9._:-]+$ example: conversation-82 XAixySessionId: name: X-Aixy-Session-ID in: header required: false description: >- Optional opaque conversation identifier recorded in Activity metadata. Reuse it for every call in a conversation. Sessions are isolated by organization, project, user and API key. Use no personal data or secrets. Invalid values are ignored. The header is not forwarded, grants no permissions and does not change routing affinity. schema: type: string minLength: 1 maxLength: 128 pattern: ^[A-Za-z0-9._:-]+$ example: conversation-82 AnthropicVersion: name: anthropic-version in: header required: true description: >- Anthropic client contract version; forwarded unchanged on native requests. Reviewed Bedrock InvokeModel routes use the required upstream envelope version. schema: type: string example: '2023-06-01' AnthropicBeta: name: anthropic-beta in: header required: false description: >- Comma-separated Anthropic beta features, forwarded on matching native requests. Reviewed destination compatibility rules may omit unused beta announcements; unsupported features in use fail explicitly. Repeated headers are additive. Preserved Bedrock InvokeModel routes carry beta features in the upstream envelope. Translated routes reject unsupported beta features. schema: type: string schemas: AnthropicTokenCountRequest: type: object required: - model - messages properties: model: type: string description: >- Provider-qualified or routing model with a supported native token counter. example: anthropic/claude-sonnet-4-5 messages: type: array items: $ref: '#/components/schemas/AnthropicMessageParam' system: oneOf: - type: string - type: array items: type: object additionalProperties: true tools: type: array items: $ref: '#/components/schemas/AnthropicTool' additionalProperties: true AnthropicTokenCount: type: object required: - input_tokens properties: input_tokens: type: integer minimum: 0 additionalProperties: true AnthropicMessageParam: type: object required: - role - content properties: role: type: string enum: - user - assistant content: oneOf: - type: string - type: array items: $ref: '#/components/schemas/AnthropicContentBlock' additionalProperties: true AnthropicTool: type: object required: - name properties: name: type: string description: type: string input_schema: type: object additionalProperties: true description: JSON Schema for a client function tool's arguments. type: type: string description: Server tools require compatible native provider support. cache_control: type: object additionalProperties: true additionalProperties: true AnthropicErrorResponse: type: object required: - type - error properties: type: type: string enum: - error error: type: object required: - type - message properties: type: type: string message: type: string additionalProperties: true request_id: type: string additionalProperties: true InferenceErrorResponse: type: object required: - error properties: error: type: object required: - message properties: message: type: string code: type: - string - 'null' type: type: - string - 'null' param: type: - string - integer - 'null' details: type: - object - 'null' additionalProperties: true additionalProperties: true type: type: string request_id: type: string additionalProperties: true AnthropicContentBlock: type: object required: - type description: >- Typed text, image, document, tool_use or tool_result content. Thinking, signed reasoning, caching and other provider blocks require compatible native support; additional fields are not a promise of translation support. properties: type: type: string example: text text: type: string source: type: object additionalProperties: true description: >- Provider image/document source, including compatible URL or base64 input. id: type: string description: Identifier of a tool_use block. name: type: string description: Function tool name. input: type: object additionalProperties: true tool_use_id: type: string description: Matching tool_use identifier for a tool_result. content: oneOf: - type: string - type: array items: type: object additionalProperties: true is_error: type: boolean thinking: type: string signature: type: string cache_control: type: object additionalProperties: true description: >- Native provider prompt-cache marker; support depends on the destination. additionalProperties: true responses: AnthropicError: description: The gateway or Anthropic-compatible provider rejected the request. headers: x-request-id: description: Aixy request identifier for correlation with Activity and support. schema: type: string example: req_example_01 content: application/json: schema: $ref: '#/components/schemas/AnthropicErrorResponse' example: type: error error: type: authentication_error message: Gateway API key is invalid or revoked request_id: req_01H... AnthropicRateLimitError: description: Aixy or the Anthropic-compatible provider rate limited the request. headers: x-request-id: description: Aixy request identifier for correlation with Activity and support. schema: type: string example: req_example_01 Retry-After: description: >- Optional retry delay. Aixy rate-limit rejections provide a positive delay in seconds; a provider may supply its own Retry-After value, including an HTTP date. required: false schema: type: string example: '60' content: application/json: schema: $ref: '#/components/schemas/AnthropicErrorResponse' example: type: error error: type: rate_limit_error message: The configured rate limit was reached. Retry later. request_id: req_01H... InferenceInternalError: description: >- An internal failure occurred. Some failures return a generic text response; record x-request-id and avoid relying on a JSON body for every server error. headers: x-request-id: description: Aixy request identifier for correlation with Activity and support. schema: type: string example: req_example_01 content: text/plain: schema: type: string example: Internal Server Error application/json: schema: anyOf: - $ref: '#/components/schemas/InferenceErrorResponse' - $ref: '#/components/schemas/AnthropicErrorResponse' NativeProviderError: description: >- A native provider may return another error status and its original payload. After streaming starts, failures can arrive inside the SSE stream instead of changing the HTTP status. Handle both HTTP errors and protocol error events. headers: x-request-id: description: Aixy request identifier for correlation with Activity and support. schema: type: string example: req_example_01 content: application/json: schema: type: object additionalProperties: true securitySchemes: GatewayApiKey: type: http scheme: bearer bearerFormat: gak_… description: >- A project-scoped Aixy API key. Create keys in the dashboard and send the secret as a Bearer token. AnthropicApiKey: type: apiKey in: header name: x-api-key description: >- A project-scoped Aixy `gak_` key sent using the Anthropic authentication header. This is equivalent to `Authorization: Bearer` and is supported for Claude Code and Anthropic SDK compatibility. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.