Key takeaways
- Claude Fable 5 makes Mythos-level capabilities available to all customers, with strong safeguards designed to make it safe for broader use.
- The model can work for days at a time in an agent harness like Claude Code.
- It can plan its approach, check progress against the goal, and refine its work as it goes.
AWS today announced the general availability of Anthropic's latest frontier model, Claude Fable 5 on Amazon Bedrock and Claude Platform on AWS. Claude Fable 5 brings Mythos-level capabilities to all customers, with strong safeguards designed to make it safe for broader use. The model is built for ambitious, long-running and complex work that previous models couldn't sustain. See Anthropic’s blog post for more details on the Mythos-level capabilities of Claude Fable 5—and the classifiers Anthropic added to make it safer for broad release.
Dive deeper: Anthropic also announced that the upgraded successor to Claude Mythos Preview, Claude Mythos 5, is available to a small group of participants, including those in Project Glasswing, approved by Anthropic.
Claude Fable 5 is part of a model family that now spans four classes: Haiku, Sonnet, Opus, and Mythos. Here's how to think about when to use it: Fable is for the most ambitious, asynchronous tasks—big projects you want the model to break down, research, create, and verify on its own over extended periods. Opus is better suited for faster, synchronous collaboration on complex tasks.
What Claude Fable 5 can do that previous Claude models can't
According to Anthropic, the new model represents a step-change in what customers can accomplish with AI. Here's what sets it apart:
- Long-running, asynchronous execution—Claude Fable 5 handles complex tasks that previous models could not sustain, running for days on coding and knowledge work without intervention.
- Advanced vision capabilities—the model understands diagrams, charts, and tables nested in files and PDFs, opening up research and document-heavy work in finance, legal, analytics, architecture, and gaming. In coding, it implements designs with high fidelity and uses vision to critique its output against goals.
- Proactive self-verification—the model updates its own skills based on learnings, develops its own harnesses and evaluations, and verifies its work.
How to access Claude Fable 5 on AWS
Customers can get started with Claude Fable 5 through Amazon Bedrock or Claude Platform on AWS:
- Amazon Bedrock—build within your existing AWS environment, maintain enterprise security and regional data residency, and scale inference. Access the model through the Bedrock Runtime console or the new Bedrock Mantle console, which offers project-aware live documentation with auto-prefilled code snippets.
- Claude Platform on AWS—use Anthropic's native platform experience when regional data residency isn't required.
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