Anthropic Claude: Claude Fable 5.1 API
Claude Fable 5.1 extends Claude Fable 5 at the same input and output prices, with cache reads at a quarter of the cost, and brings stronger long-running agentic coding, multistep research, and document, spreadsheet, and slide work.
- Context window: 1,000,000 tokens
- Max output: 128,000 tokens
- Input: text, image
- Output: text
- Reasoning: Supported
- Tool calling: Supported
- File input: Supported
- Released: 2026-08-31
- Knowledge cutoff: 2025-11-30
Frequently Asked Questions
What is the context window of Claude Fable 5.1?
Claude Fable 5.1 supports a context window of up to 1,000,000 tokens.
Does Claude Fable 5.1 support function calling?
Yes. Claude Fable 5.1 supports tool / function calling.
Does Claude Fable 5.1 support reasoning?
Yes. Claude Fable 5.1 is a reasoning-capable model.
What is the knowledge cutoff of Claude Fable 5.1?
The knowledge cutoff of Claude Fable 5.1 is 2025-11-30.