Claude Fable 5 from Anthropic back on Amazon Bedrock with stronger guardrails

Update: This article was originally published on June 9, 2026. Anthropic’s Claude Fable 5 is available again on Amazon Bedrock starting July 1, with even stronger guardrails to prevent misuse.

We believe that making the capabilities of these advanced models available to all customers in a secure, privacy preserving environment is critical to ensuring that they can get the many benefits without creating security risks. Learn more about how we work to safely release frontier models to our customers.

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 executes coding and knowledge work tasks for extended periods 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, and develops its own harnesses and evaluations.

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 and scale inference workloads. Access the model programmatically using the Anthropic Messages API, or use it in the Bedrock console Playground.
Claude Platform on AWS: Access through use Anthropic's native platform experience.

Customers can also use Claude Fable 5 with Advanced Prompt Optimization on Amazon Bedrock, which benchmarks prompts against evaluation criteria and outputs production-ready rewrites.