Claude Fable 5.1 (batch)

Claude Fable 5.1 is Anthropic's reasoning-focused model with a 1 million token context window, designed for complex analytical and agentic tasks.

Strengths

Excels at multi-step reasoning, long-context analysis, and sustained autonomous work over extended interactions.

Best for

Batch processing of reasoning-heavy workloads where asynchronous turnaround is acceptable and context window depth matters.

Limitations

The batch variant trades real-time availability for efficiency; Claude Opus 5.5, released the same month, is positioned as the flagship for the most demanding reasoning tasks.