v0, Vercel's AI-powered full-stack app builder, has re-added Claude Fable 5 to its model picker. The announcement came directly from the v0 team on X: "Claude Fable 5 is back in v0." The move follows the broader restoration of Fable 5 access across Anthropic's ecosystem after a roughly three-week suspension tied to a US government export control directive.
If you missed the context: Fable 5 and Mythos 5 were suspended by export control on June 12, 2026. In compliance with the US Government's directive, access to Claude Fable 5 was suspended on AI Gateway for all users. The restriction has since been lifted, and access to Claude Fable 5 and Claude Mythos 5 has been restored.
What Fable 5 actually is
For those who haven't used it yet, Fable 5 is a significant step up from the previous Claude generation. Claude Fable 5 is Anthropic's most capable widely released model, built for the most demanding reasoning and long-horizon agentic work. The term "Mythos-class" refers to Anthropic's top capability tier, designed specifically for multi-step autonomous tasks.
A Mythos-class model, Fable 5 is a notable step up over prior Claude models on long-running, ambiguous, multi-step tasks, executing end-to-end on work that previously required frequent human check-ins. The model sustains productive output across multi-day runs and dependably dispatches parallel sub-agents, and lower effort settings often match what prior Claude models produced at their highest effort.
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