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v1

latestOpenAPI 3.0.02026-07-26117076.0 KB
Text Series

Claude Messages API

Send requests in the Claude Messages format. For the latest request parameter definitions, refer to the official Anthropic documentation: https://platform.claude.com/docs/en/api/messages/create

post/v1/messages

Request body

modelstring required

Model name. Example: claude-sonnet-4-5-20250929.

max_tokensinteger

Maximum number of tokens to generate.

streamboolean

Whether to use streaming output.

stop_sequencesstring[]

Stop sequences. The model stops when it encounters any of these strings.

metadataobject

Additional metadata such as user_id.

Example request

{
  "model": "claude-sonnet-4-5-20250929",
  "messages": [
    {
      "role": "user",
      "content": "Summarize the purpose of feature canary releases in two sentences."
    }
  ],
  "max_tokens": 1024,
  "system": "You are a product announcement editor, keep it objective and concise.",
  "cache_control": {
    "type": "ephemeral",
    "ttl": "1h"
  },
  "output_config": {
    "effort": "high",
    "format": {
      "type": "json_schema"
    }
  },
  "thinking": {
    "type": "enabled",
    "budget_tokens": 2048,
    "display": "summarized"
  },
  "tools": [
    {
      "name": "get_weather",
      "description": "Fetch the weather by city name."
    }
  ],
  "tool_choice": "auto"
}

Response

Message created

codeinteger

Example response

{
  "code": 200,
  "data": {
    "id": "msg_013zva2CMHNLnXJNN3QKQ2EF",
    "type": "message",
    "role": "assistant",
    "content": [
      {
        "type": "text",
        "text": "Hello! I'm Claude. Nice to meet you.",
        "source": {
          "type": "base64",
          "media_type": "image/png"
        }
      }
    ],
    "model": "claude-sonnet-4-5-20250929",
    "stop_reason": "end_turn",
    "usage": {
      "input_tokens": 10,
      "output_tokens": 13
    }
  }
}