PANews reported on June 10th that Anthropic released a public version of its Mythos model on Tuesday, but with restrictions prohibiting its use in high-risk areas such as cybersecurity. Anthropic stated that the new Claude Fable 5 is the most powerful model Anthropic has ever built for wider application, praising its performance in software engineering and data analysis. Anthropic had previously announced that Mythos had discovered thousands of software vulnerabilities, and subsequently limited the model's use to approximately 200 organizations, including the US government, through its "Glasswing" program. Anthropic stated that extensive testing has been conducted to ensure that users cannot manipulate Claude Fable 5 to bypass its guidelines and perform restricted operations.

Dianne Penn, Head of Product Management, Research and Labs at Anthropic, stated that based on early customer feedback, while Fable 5 is more expensive, it requires fewer tokens to execute tasks, thus reducing the overall cost per task. Anthropic also stated that users with access to the Claude Mythos preview version (i.e., the version without security measures) will be able to upgrade to the new Claude Mythos 5. Both models are priced at $10 per million input tokens and $50 per million output tokens.