anthropic/claude-fable-5.1Claude Fable 5.1 is Anthropic’s proprietary AI model, released Sep 1, 2026. It scores 166 on the Epoch Capabilities Index, costs $10/M input and $50/M output tokens, and handles a 1M-token context window. Its strongest use case is coding, where it ranks in the 98th percentile of the models Model Beat tracks.
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: long code refactors, front-end and visual…
Scores on standardized evaluations. Higher is better — and rank shows where Claude Fable 5.1 lands among all models tracked on Model Beat.
Abstract visual reasoning
Harder abstract reasoning
Graduate-level scientific reasoning
Frontier of human expert knowledge
Factual accuracy & hallucination
Novel ML problem-solving
Code performance optimization
Scientific research coding
Human-rated web development
Olympiad-qualifier math
Multi-step agentic tasks
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: long code refactors, front-end and visual…
Claude Fable 5.1 is an AI model developed by Anthropic, part of the Claude family, released Sep 1, 2026.
Claude Fable 5.1's list price from Anthropic is $10 per million input tokens and $50 per million output tokens.
Claude Fable 5.1 supports a context window of up to 1M tokens.
On standardized evaluations tracked by Epoch AI, Claude Fable 5.1 scores 88.2% on GSO (code optimization), 63.1% on SciCode, 92.9% on WeirdML.
Claude Fable 5.1 is a proprietary model (API access), available through its provider's API rather than as a downloadable open-weight model.
Benchmark data from Epoch AI (CC BY) and Artificial Analysis; pricing, specs & descriptions from OpenRouter. Data updated Oct 29, 2026.