All videos
0:00 / 0:00
ai

Meet Claude Fable 5.1

Anthropic1 September 2026Watch on YouTube

Part of series

Ep. 11 · Opus Anthropic Charts

View the series

What you'll learn

  • You discover what Claude Fable 5.1 is, the latest upgrade to Anthropic's most capable class of models
  • You learn that the model excels at complex, long-running tasks such as long mathematical proofs or contracts with hundreds of cross-references
  • You see how the model avoids shortcuts and can fix the root causes of software issues
  • You learn that at lower effort levels Fable 5.1 can achieve similar or better results than Fable 5 at a much lower cost
  • You get an early glimpse of how AI can contribute to scientific progress through research capabilities

Frequently asked questions

What is Claude Fable 5.1?
Claude Fable 5.1 is the latest upgrade to Anthropic's most capable class of models. It is available everywhere today.
At which tasks does Claude Fable 5.1 excel?
The model excels at complex, multi-step work such as a long mathematical proof or a contract with hundreds of cross-references.
How does the cost of Fable 5.1 compare to Fable 5?
At lower effort levels, Fable 5.1 can achieve similar or better results than Fable 5 at a much lower cost.
How does Fable 5.1 approach software issues?
The model avoids shortcuts and is smart enough to fix the root causes of software issues.

Topics

Read next

Description from the channel

Claude Fable 5.1 is the latest upgrade to our most capable class of models. It excels at complex, long-running tasks, and its research capabilities offer an early glimpse of how AI will contribute to scientific progress. It excels at complex, multi-step work, like a long mathematical proof or a contract with hundreds of cross-references. It avoids shortcuts and is smart enough to fix the root causes of software issues. Across our benchmarks, Fable 5.1 sets a new standard, and at lower effort levels it can achieve similar or better results than Fable 5 at a much lower cost. Claude Fable 5.1 is available everywhere today. Read more: https://www.anthropic.com/claude-fable-and-mythos-5-1