Anthropic launches Claude Fable 5 and Mythos 5 models
Anthropic has launched Claude Fable 5, a general-availability model it describes as state-of-the-art on nearly all tested benchmarks, alongside Claude Mythos 5, a restricted version with lifted safeguards for cyberdefenders and infrastructure providers.
Score breakdown
Fable 5 represents Anthropic's most capable generally available model to date, and the dual launch with Mythos 5 introduces a tiered access model that pairs broad public release with a restricted, safeguard-lifted variant for vetted cyberdefense use cases — a structure Anthropic describes as central to releasing powerful models both safely and quickly.
- 01Claude Fable 5 is described as state-of-the-art on nearly all tested benchmarks across software engineering, knowledge work, vision, and scientific research.
- 02Fable 5 ships with conservative safeguards that route some queries to Claude Opus 4.8; these trigger in less than 5% of sessions on average.
- 03Claude Mythos 5 is the same underlying model as Fable 5 but with safeguards lifted in some areas, available initially only to cyberdefenders and infrastructure providers.
Anthropic launched Claude Fable 5 and Claude Mythos 5 on June 9, 2026. Fable 5 is a Mythos-class model made safe for general use, and Anthropic states its capabilities exceed those of any model it has previously made generally available. The model is described as state-of-the-art on nearly all tested benchmarks, with performance gains that grow larger as tasks become longer and more complex. Highlighted capabilities include software engineering — Stripe reported that Fable 5 compressed months of engineering into days, completing a codebase-wide migration in a 50-million-line Ruby codebase in a single day that would otherwise have taken a full team over two months. On Cognition's FrontierCode evaluation, Fable 5 scores highest among frontier models even at medium effort. In knowledge work, Fable 5 achieved the highest score on Hebbia's Finance Benchmark for senior-level reasoning, and IMC reported it aced their trading-analysis evaluations nearly across the board. In vision tasks, Fable 5 completed Pokémon FireRed using only raw game screenshots with no maps or navigation aids — a task previous Claude models required a complex helper harness to attempt.
Because Fable 5's cybersecurity capabilities could be misused, Anthropic launched it with conservative safeguards that redirect certain queries to Claude Opus 4.8.
Because Fable 5's cybersecurity capabilities could be misused, Anthropic launched it with conservative safeguards that redirect certain queries to Claude Opus 4.8. These safeguards trigger in less than 5% of sessions on average, and Anthropic states it is working to reduce false positives as more capable models arrive. Claude Mythos 5 is the same underlying model with safeguards lifted in some areas, initially available only to a small group of cyberdefenders and infrastructure providers through Project Glasswing, a collaboration with the US government and an upgrade to Claude Mythos Preview. Anthropic describes Mythos 5 as having the strongest cybersecurity capabilities of any model in the world, and intends to expand access through a broader trusted access program. Both models are priced at $10 per million input tokens and $50 per million output tokens, which Anthropic describes as less than half the price of Claude Mythos Preview.
Key facts
- 01Claude Fable 5 is described as state-of-the-art on nearly all tested benchmarks across software engineering, knowledge work, vision, and scientific research.
- 02Fable 5 ships with conservative safeguards that route some queries to Claude Opus 4.8; these trigger in less than 5% of sessions on average.
- 03Claude Mythos 5 is the same underlying model as Fable 5 but with safeguards lifted in some areas, available initially only to cyberdefenders and infrastructure providers.
- 04Mythos 5 is initially deployed through Project Glasswing, a collaboration with the US government, as an upgrade to Claude Mythos Preview.
- 05Stripe reported Fable 5 completed a codebase-wide migration in a 50-million-line Ruby codebase in one day — a task estimated to take a full team over two months by hand.
- 06Fable 5 completed Pokémon FireRed using only raw game screenshots, requiring no maps, navigation aids, or helper harness.
- 07Both models are priced at $10 per million input tokens and $50 per million output tokens, described as less than half the price of Claude Mythos Preview.
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