Creating Formatted Output

POST

/v1/messages

Given a prompt, the model will return one or more predicted completions, and can also return the probability of alternative tokens at each position.

Create a completion for the provided prompt and parameters

Official documentation: https://docs.anthropic.com/en/docs/agents-and-tools/tool-use/overview#how-tool-use-works

Request

Authorization

Provide your bearer token in the

Authorization

header when making requests to protected resources.

Example:

Authorization: Bearer ********************

Header Params

Body Params application/json

Examples

Responses

🟢200OK

application/json

Body

Request Example

Shell

JavaScript

Java

Swift

curl --location --request POST '/v1/messages' \
--header 'Accept: application/json' \
--header 'anthropic-beta: structured-outputs-2025-11-13' \
--header 'Authorization: Bearer <token>' \
--header 'Content-Type: application/json' \
--data-raw '{
    "model": "claude-sonnet-4-5-20250929",
    "max_tokens": 1024,
    "messages": [
      {
        "role": "user",
        "content": "Extract the key information from this email: John Smith (john@example.com) is interested in our Enterprise plan and wants to schedule a demo for next Tuesday at 2pm."
      }
    ],
    "output_format": {
      "type": "json_schema",
      "schema": {
        "type": "object",
        "properties": {
          "name": {"type": "string"},
          "email": {"type": "string"},
          "plan_interest": {"type": "string"},
          "demo_requested": {"type": "boolean"}
        },
        "required": ["name", "email", "plan_interest", "demo_requested"],
        "additionalProperties": false
      }
    }
  }'

Response Example

{
    "id": "chatcmpl-123",
    "object": "chat.completion",
    "created": 1677652288,
    "choices": [
        {
            "index": 0,
            "message": {
                "role": "assistant",
                "content": "\n\nHello there, how may I assist you today?"
            },
            "finish_reason": "stop"
        }
    ],
    "usage": {
        "prompt_tokens": 9,
        "completion_tokens": 12,
        "total_tokens": 21
    }
}

Modified at 2026-03-06 15:34:51

Create Function Call (Streaming)

Create Thinking Chat