Anthropic's most powerful publicly available AI model is now in users' hands, as the rollout of Claude Fable 5 — released this week alongside a restricted counterpart, Claude Mythos 5 — extended to Amazon Bedrock and enterprise plans, putting what the company calls a 'Mythos-class' system into general circulation for the first time.
Fable 5's capabilities exceed those of any model Anthropic has previously made generally available, with state-of-the-art results on nearly all tested benchmarks spanning software engineering, knowledge work, vision and scientific research. The company says the model's advantage over its predecessors grows with task length, and that it can work autonomously for longer than any previous Claude model. Early customer Stripe reported that Fable 5 performed a codebase-wide migration in a day that would otherwise have occupied a team for more than two months.
The release is notable as much for its safety architecture as its capability. Fable 5 ships with safeguards that route queries on certain high-risk topics — including areas of cybersecurity and biology — to the older Claude Opus 4.8 model instead. Anthropic says the routing is tuned conservatively and triggers in fewer than 5% of sessions on average.
For users with a legitimate need for the unrestricted system, Anthropic launched Claude Mythos 5 — the same underlying model with safeguards lifted in some areas — available initially to cyberdefenders and infrastructure providers through Project Glasswing, a collaboration with the US government.
The two-tier release follows the company's own public warnings that frontier AI capabilities are becoming dangerous in narrow domains, a tension TechCrunch noted in reporting that Anthropic shipped its most powerful public model days after cautioning that AI is 'getting too dangerous' in some respects.
Pricing is aggressive for a frontier model: $10 per million input tokens and $50 per million output tokens, less than half the cost of the earlier Mythos Preview, with Fable 5 included on paid Claude plans through June 22. The model is also available through Amazon Bedrock for AWS customers.
The launch sharpens the competitive picture in a frenetic month for AI: Apple's WWDC made Claude an option on the iPhone through its multi-AI Extensions system, Google's Gemini 3.5 Pro is expected within weeks, and Anthropic itself filed confidentially for an IPO earlier this month at a reported valuation near $965 billion.
Not every partner is fully on board: Microsoft has objected to aspects of the model's data retention policy for enterprise deployments, an early sign of the contractual friction that comes with distributing frontier models through rival clouds.