Anthropic has released Claude Fable 5, the first publicly available model in its new “Mythos” class — a capability tier that sits above the Opus line. It launched June 9, and the headline number is coding: Fable 5 scores 80.3% on SWE-Bench Pro, up from Opus 4.8’s 69.2% and well ahead of GPT-5.5 at 58.6%.
## What Claude Fable 5 does
Fable 5 is positioned as state-of-the-art across most benchmarks Anthropic tests — software engineering, knowledge work, vision, and scientific research — not just coding. It’s available through the Claude API, the Claude apps, and Amazon Bedrock, priced at $10 per million input tokens and $50 per million output, exactly double Opus 4.8. Paid Claude subscribers get free access during an introductory window through June 22.
## Why it matters
The release comes with an unusual framing: Fable 5 is the public version with safeguards on, while a safeguards-lifted “Mythos 5” is restricted to vetted infrastructure providers and cybersecurity researchers. Anthropic tuned the public guardrails conservatively — they trigger in under 5% of sessions. Shipping a frontier-class model while explicitly gating its most powerful form is a bet on how to release fast and safely at once.
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