Claude Fable 5.1
Claude Fable 5.1 improves on Claude Fable 5 across the board, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work such as long code refactors and front-end work.
Specifications
| Lab | Anthropic |
|---|---|
| Context window | 1M tokens |
| Input price | $10.00/1M |
| Output price | $50.00/1M |
| Release | Sep 2026 |
Strengths
- Frontier-tier coding and agentic performance
- Million-token context window
- Reliable multi-step tool use
- Strong long-form knowledge work
Weaknesses
- High input and output pricing
- New version has limited independent benchmark history
Best for
- Autonomous software engineering
- Long-running research agents
- Complex tool-using workflows
In Depth: Claude Fable 5.1
Summary
Claude Fable 5.1 is an AI model from Anthropic.
Released in Sep 2026. It takes text, image, and file input and produces text output, with a context window of 1M tokens. Input pricing is $10.00 per 1M tokens and output is $50.00 per 1M tokens on OpenRouter.