Models

Claude Fable 5.1

Anthropic · September 2026

For hard problems, long documents, and work that runs over many steps.

  • Modalities

  • Context window

    1,000,000 tokens, ≈ 750,000 words · about 3,000 pages

  • Max output

    128,000 tokens, ≈ 96,000 words in a single answer

  • Knowledge cutoff

    June 2026

Reasoning effort

Default: High

  • Low

  • Medium

  • High

  • X-High

  • Max

Providers

Files you can attach

  • ImagesJPG, PNG, GIF, WEBP
  • DocumentsPDF
  • Text and codeTXT, MD, CSV, TSV, RPT, LOG, PY, TS, TSX, JS, JSX, CS, GO, JAVA, KT, SWIFT, CPP, C, H, PHP, RB, SQL, SH, PS1, HTML, CSS, SCSS, JSON, YAML, YML, XML, INI

Tools

  • Web searchSupported
  • Code interpreterSupported

Features

  • StreamingSupported
  • Function callingSupported
  • Structured outputsSupported
  • Fine-tuningNot supported

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