Microsoft restricts Claude Fable for employees over data retention concerns

Anthropic has launched its first Mythos-class AI model, Claude Fable, which is raising concerns within Microsoft. Sources indicate that Microsoft is restricting the use of Claude Fable 5 for employees due to new data retention requirements imposed by Anthropic. While Microsoft quickly rolled out Claude Fable 5 to its GitHub Copilot and Foundry customers, the model is not available in the internal model picker for Microsoft employees. All other Claude models remain available internally, operating under Zero Data Retention (ZDR) rules.