What is Claude Fable 5?

Claude Fable 5 is Anthropic's new general-use, Mythos-class AI model that delivers state-of-the-art capabilities in software engineering, vision, and scientific research. It is designed for developers, engineering teams, and enterprises seeking advanced autonomous reasoning.

What is Claude Mythos 5 and how does it differ from Fable 5?

Claude Mythos 5 is the same underlying model as Fable 5 but has its safeguards lifted in select areas. It is restricted to a small group of cyberdefenders and infrastructure providers via Project Glasswing in partnership with the US government.

How much do Claude Fable 5 and Mythos 5 cost?

Both Claude Fable 5 and Mythos 5 are priced at $10 per million input tokens and $50 per million output tokens, which is less than half the price of the previous Claude Mythos Preview model.

What are the fallback safeguards in Claude Fable 5?

To prevent misuse of Fable 5's advanced capabilities (e.g., in cybersecurity), Anthropic routes sensitive queries to Claude Opus 4.8. These conservative safeguards trigger in less than 5% of user sessions.

What real-world coding improvements does Claude Fable 5 show?

Fable 5 demonstrates high autonomy in coding, with Stripe reporting it completed a codebase-wide migration on a 50-million-line Ruby codebase in a single day—a task that would normally take a team over two months.

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Claude Fable 5 and Mythos 5: SOTA Autonomy and Safeguards

Anthropic launched Claude Fable 5 and Mythos 5 June 9, 2026 — SOTA autonomy, coding, and safeguards. Live again July 1 after export controls lifted June 30.

Jun 10, 2026·1 min read·Yash Thakker

ClaudeAnthropicLLM ModelsAI UpdatesCybersecurity

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Claude Fable 5 and Mythos 5: SOTA Autonomy and Safeguards

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Update — July 7, 2026: Fable leaves included subscription plans after 11:59:59pm PT; Anthropic aims to restore when capacity allows. Subscription billing guide →

Claude Fable 5 and Mythos 5: SOTA Autonomy and Safeguards

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