Anthropic has launched Claude Fable 5 for general public use as well as Claude Mythos 5 for a restricted group of cybersecurity and infrastructure partners. This move will mark the company’s first release of a Mythos-class model to the broader public.
Both models launch on June 9, 2026 and are priced at $10 per million input tokens and $50 per million output tokens. Surprisingly, it is less than half the cost of Claude Mythos Preview.
As Anthropic puts it:
Fable 5’s capabilities exceed those of any model we’ve ever made generally available. It is state-of-the-art on nearly all tested benchmarks of AI capability, showing exceptional performance in software engineering, knowledge work, vision, scientific research, and many other areas. The longer and more complex the task, the larger Fable 5’s lead over our other models.
As per Anthropic, Claude Fable 5 has nearly all tested AI capability benchmarks. The new model comes with exceptional performance in software engineering, knowledge work, vision, scientific research, and long-horizon agentic tasks.
Stripe reported in early testing that Fable 5 compressed months of engineering into days, performing a codebase-wide migration across a 50-million-line Ruby codebase in a single day. Otherwise, that would have taken an entire team over two months.
On Cognition’s FrontierCode evaluation, which tests models against high-quality production coding standards, Fable 5 scored highest among all frontier models. It also set new state-of-the-art results on Hebbia’s Finance Benchmark for senior-level reasoning, complex vision tasks, and long-context memory work.
Because Mythos-class capabilities create real risks of misuse (particularly in cybersecurity and biological research), Fable 5 launches with new safety classifiers. Queries touching cybersecurity, biology and chemistry, or AI distillation automatically route to Claude Opus 4.8 instead of Fable 5.
Anthropic says classifiers trigger in under 5% of sessions on average. Also, its external bug bounty produced no universal jailbreaks after over 1,000 hours of testing.
Claude Mythos 5 carries the same underlying capabilities as Fable 5. However, with Fable 5, the cyber safeguards got lifted for partners in Project Glasswing, Anthropic’s US government-backed cyber defense program. Anthropic plans to expand Mythos 5 access through a broader trusted access program in the coming weeks. They will open a separate biology-focused trusted access track for select biomedical researchers shortly after.
Fable 5 is available on the Claude API under the model string claude-fable-5. It is included at no extra cost on Pro, Max, Team, and seat-based Enterprise plans through June 22, 2026.
