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Claude Fable 5

Available · Language, Multimodal, Reasoning · Milestone

Claude Fable 5 is a language model in Anthropic's Fable line, launched on 9 June 2026 on the Claude apps, the API and major cloud platforms. Anthropic describes it as a Mythos-class model whose classifiers route some cybersecurity, biology and chemistry requests to Claude Opus 4.8. Access was suspended on 12 June 2026 under US export controls and restored on Anthropic's own platforms from 1 July. [1] [2] [3] Primary source

Timeline of Claude Fable 5 →

Claims and evidence

  • Released Primary source[1] [2]Availability: Released
  • Status Available Primary source[2]Availability [4]Model status table [3]update of Jul 1, 2026
    • Change · Availability Open to all customers, whereas Claude Mythos Preview was an invitation-only research preview for Project Glasswing participants.Compared with Claude Mythos Preview Primary source[1] [5]June 9, 2026; April 7, 2026
    • Change · Other Priced at 10 USD input and 50 USD output per million tokens, which Anthropic says is less than half the Mythos Preview price.Compared with Claude Mythos Preview Primary source[1]
    • Change · Reasoning Adaptive thinking is the only thinking mode; disabling thinking or setting a manual thinking budget returns an error.Compared with Claude Mythos Preview Primary source[5]June 9, 2026 [6]Migrating from Claude Mythos Preview
    • Input text, image Primary source[2]Capabilities: Input and output
    • Output text Primary source[2]Capabilities: Input and output
    • Context window 1M tokens Primary source[2]Capabilities: Context window
    • Parameters Not disclosedNot disclosed by Anthropic. No claim madeNo source
    • Access API, consumer app, cloud partner Primary source[1]availability section [2]Availability: Platforms

    Lineage

    Predecessors

    No known predecessor.

    Successors

    Based on

    Not derived from another model.

    Variants and derived

    Siblings

    None recorded.

    All ancestors

    None.

    All descendants

    Variants

    No variants recorded in this record.

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