Claude Fable 5.1

Claude Fable 5.1 is a Claude model for demanding reasoning and long-horizon agentic work. It is part of the claude-fable line, released after Claude Fable 5. It has a context window of 1,000,000 tokens and a maximum output of 128,000 tokens. Pricing starts at $10.00 per million input tokens and $50.00 per million output tokens, with cached input at $0.25 per million tokens. The weights are not open. It supports reasoning mode and tool calling, and accepts image, PDF, and text inputs, returning text. Its knowledge cutoff is June 2026.

Against Claude Fable 5: input $3.00 to $10.00, output $18.50 to $50.00, cached input $0.30 to $0.25.

Range across the hosts that serve it: up to $12.00 per 1M input tokens.

• ·1M token context window for long-horizon tasks
• ·128K token max output for detailed responses
• ·Reasoning mode and tool calling built in
• ·Accepts image, PDF, and text inputs
• ·Cached input at $0.25 per million tokens

• Reach for it for complex multi-step reasoning tasks
• Reach for it for long-horizon agentic workflows
• Reach for it for processing large documents or codebases
• Reach for it for tasks requiring image and PDF understanding

16 hosts serve this model at the price above · the maker's documentation

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8 signals of the archive mention this model, each scored against the published bar. This list is rebuilt from the archive at every build, so it cannot go stale.

The registry keeps the six most recent versions of a line. Older ones stay in the file and can be surfaced without a rebuild.

What is the context window and maximum output?

Context window is 1,000,000 tokens, maximum output is 128,000 tokens.

What is the pricing?

From $10.00 per million input tokens and $50.00 per million output tokens, with cached input at $0.25 per million tokens.

Does it support tool calling and reasoning?

Yes, it supports reasoning mode and tool calling.