# Claude Fable 5.1: AI model fact sheet

- **Provider:** anthropic
- **Released:** 2026-09-01
- **Context window:** 1,000,000 tokens
- **API pricing:** $10.00 / 1M input, $50.00 / 1M output
- **OpenRouter ID:** anthropic/claude-fable-5.1
- **Capabilities:** conversation, reasoning, code-generation, analysis, agentic-tool-use, tool-use, planning, web-design

Claude Fable 5.1 is a direct update to Fable 5, with its largest gains in agent coding, long-running workflows and knowledge work. Anthropic calls out long refactors, front-end generation, finance and analysis, with shorter plans and summaries than Fable 5.

Source: real side-by-side outputs, pricing and specs at https://rival.tips/models/claude-fable-5.1