Claude Fable 5 API

Authentication

Send your API key in the Authorization header using Bearer token format.

Authorization: Bearer <your-api-key>

Create a Message

The endpoint is compatible with Claude-style Messages requests and supports both non-streaming JSON responses and streaming responses.

curl https://api.defapi.org/api/v1/messages \
  -H "Authorization: Bearer dk-1234567890abcdef" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "anthropic/claude-fable-5",
    "messages": [
      {
        "role": "user",
        "content": "Explain how to migrate a large Next.js codebase."
      }
    ],
    "max_tokens": 512,
    "temperature": 0.7,
    "stream": false
  }'

Request Parameters

Streaming Request

Set stream to true to receive server-sent event style chunks.

{
  "model": "anthropic/claude-fable-5",
  "messages": [
    {
      "role": "user",
      "content": "Tell me a short story about a brave knight."
    }
  ],
  "max_tokens": 512,
  "temperature": 0.7,
  "stream": true
}

Non-Streaming Response

A successful non-streaming request returns the assistant message and token usage.

{
  "id": "msg_01ABCDxyz",
  "type": "message",
  "role": "assistant",
  "model": "anthropic/claude-fable-5",
  "stop_reason": "end_turn",
  "stop_sequence": null,
  "content": [
    {
      "type": "text",
      "text": "Hello! How can I help you today?"
    }
  ],
  "usage": {
    "input_tokens": 20,
    "output_tokens": 50,
    "cache_read_input_tokens": 0,
    "cache_creation_input_tokens": 0
  }
}

Error Responses