Microsoft blocks Claude Fable 5 for staff over data
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- Anthropic released Claude Fable 5, the first Mythos‑class AI model, yesterday.
- Microsoft is restricting internal employee access to Claude Fable 5 because Anthropic’s new data‑retention policy requires retaining prompts and outputs for up to 30 days, or up to two years for policy‑violating content.
- Microsoft’s legal team is reviewing the retention changes, citing concerns over customer data and confidential information.
- Microsoft continues to offer other Claude models internally under Zero Data Retention (ZDR) rules, while Claude Fable 5 is unavailable in the employee model picker.
- Anthropic’s safety classifiers for Fable 5 depend on retained data, prompting the retention policy that stores flagged content for up to two years.
- Microsoft declined to comment on the restriction.
Why it matters: Microsoft employees lose access to the latest Mythos model, while Anthropic’s retention policy could expose Microsoft to liability over stored customer prompts, forcing a legal review that may delay broader corporate adoption of the technology. The policy stores prompts for 30 days and flagged content for up to two years, raising compliance concerns.
