AI model · by Anthropic
Claude Fable 5.1
Claude Fable 5.1 is Anthropic's model geared toward programming and knowledge-based work, featuring research tools aimed at advancing science.
- Released 1 Sept 2026
- 1M tokens context
- Closed weights
- Checked against Anthropic's page 19 Oct 2026
What Claude Fable 5.1 is for
Anthropic says Claude Fable 5.1 is designed for programming and knowledge tasks, and its research abilities hint at how AI may help move science forward. On September 1, 2026, Anthropic announced it is open to Pro, Max, Team, and Enterprise subscribers handling their most demanding knowledge and coding projects. It can also be reached through the Claude Platform, via approved marketplaces, and on Amazon Web Services, Google Cloud, and Microsoft Foundry.
What Anthropic says it does well
- Most capable model for ambitious coding projects, including features spanning an entire codebase, code review, performance work, and multi-day autonomous sessions.
- Handles long-running agent jobs: plans work, uses needed tools, recovers when a step fails, and keeps the user updated.
- Avoids easy-seeming shortcuts and fixes root causes of problems rather than symptoms.
- Understands diagrams, charts, and tables nested in files and PDFs, aiding document-heavy work in finance, legal, analytics, and architecture.
Where to use it
- Claude Pro, Max, Team, and Enterprise plans, for individuals and organizations.
- Claude Platform (API, natively), through available marketplaces, and on Amazon Web Services, Google Cloud, and Microsoft Foundry, for developers.
Limits Anthropic mentions
- Using Fable requires 30-day data retention for safety monitoring by default.