Fable 5.1

Claude Fable 5.1 improves on Fable 5 across the board. The biggest gains are in agentic coding, long-running agent workflows, and knowledge work such as long code refactors and front-end builds.

client.chat.completions.create(    model="claude-fable-5-1",    messages=[        {"role": "user", "content": "Hello"},    ],)