Anthropic’s Fable 5 model is available again, the company announced today. Claude users now see the option to use Fable 5, with Anthropic rolling out an in-app message.
Until July 7, eligible Claude subscribers can use up to 50% of their plan’s weekly usage limit on Fable 5. After reaching this limit, Fable 5 usage will require credits. After July 7, Fable will be available via usage credits.
Fable 5 is Anthropic’s first Mythos class model available to the public, and it was first released on June 9. Fable 5’s capabilities exceed those of any model it has made generally available, and it has demonstrated “outstanding performance” for software engineering, knowledge work, vision, scientific research, and more. It outperforms Opus models on longer and more complex tasks. Fable 5 can operate autonomously longer than any previous Claude model.
Although Anthropic released Fable 5 with conservative safeguards to prevent misuse, the Trump administration applied export controls to the model, forcing Anthropic to restrict access to foreign nationals. Anthropic had no way to verify the nationality of people using its models, so it had to suspend access to Fable 5. At the same time, Anthropic also had to restrict access to Mythos 5, the next model in its Project Glasswing initiative for large companies and federal agencies seeking help defending critical infrastructure.
The order came after Amazon researchers found a prompt capable of bypassing Fable’s protections and the model discovered software vulnerabilities. Anthropic investigated and found that older models and models from competing companies could also locate the same vulnerabilities. Anthropic ended up delivering a new classifier that blocks the technique in more than 99% of cases.
Fable 5 is available for Pro, Max, Team, and select Enterprise plans. Anthropic has also restored access to Mythos 5 for US organizations that are part of Project Glasswing.
Anthropic says it is deepening its cooperation with the U.S. government on new preliminary testing, information sharing and research collaboration.
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