Creates a message using the Anthropic Messages API format. Drop-in replacement for the Anthropic API.

When stream: true, the response is sent as Server-Sent Events (SSE). Each event has a type field indicating the event kind (message_start, content_block_delta, message_delta, message_stop).

Authorization

x-api-key<token>

Anthropic-style API key header.

In: header

Request Body

application/json

Anthropic Messages request.

TypeScript Definitions

Use the request body type in TypeScript.

Messages request body (https://docs.anthropic.com/en/api/messages).

pub so downstream crates (notably bitrouter-cloud) can derive an OpenAPI schema from the canonical wire shape without redeclaring it.

max_tokens?|

Formatuint32

Range0 <= value

Defaultnull

messages*array<>

model*string

output_config?|

Structured-output + reasoning config — format (json_schema) is promoted to the canonical response_format and effort to the canonical reasoning effort. Sibling keys pass through via extra. https://platform.claude.com/docs/en/build-with-claude/structured-outputs

stop_sequences?array<string>|

Custom stop sequences. Promoted to the canonical stop slot, so it can render as a Chat Completions stop or a Gemini stopSequences. https://docs.anthropic.com/en/api/messages#body-stop-sequences

Defaultnull

stream?boolean

Defaultfalse

system?unknown

String or an array of {type:"text", text} blocks (#227 → #228).

Defaultnull

temperature?|

Formatdouble

Defaultnull

tools?array<>

top_k?|

Top-k sampling. Promoted to the canonical top_k slot so it translates across protocols (e.g. to a Gemini upstream's generationConfig.topK). https://docs.anthropic.com/en/api/messages#body-top-k

Formatuint32

Range0 <= value

Defaultnull

top_p?|

Formatdouble

Defaultnull

Response Body

`application/json`

curl -X POST "https://example.com/v1/messages" \  -H "Content-Type: application/json" \  -d '{    "messages": [      {        "content": null,        "role": "string"      }    ],    "model": "string"  }'

{  "content": [    {      "text": "string",      "type": "string"    }  ],  "id": "string",  "model": "string",  "role": "string",  "stop_reason": "string",  "stop_sequence": "string",  "type": "string",  "usage": {    "cache_creation_input_tokens": 0,    "cache_read_input_tokens": 0,    "input_tokens": 0,    "output_tokens": 0  }}

{  "error": {    "code": "string",    "message": "string"  }}

{  "error": {    "code": "string",    "message": "string"  }}

{  "error": {    "code": "string",    "message": "string"  }}

Create message

Authorization

Request Body

Response Body

200application/json

400application/json

402application/json

404application/json

`application/json`

`application/json`

`application/json`