Claude Fable 5.1

Anthropic's current flagship for coding and knowledge work.

Knowledge cutoff Jun 2026. Adaptive thinking is always on. $0.40/$0.70 per M; cache reads $0.04/M.

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{
  "model": "claude-fable-5-1",
  "messages": [
    {
      "role": "user",
      "content": "Hello, world."
    }
  ]
}