Claude Fable 5.1 and Mythos 5.1 require 30-day data retention

UpdateSep 1, 2026VerifiedAdded Sep 22, 2026

Like Claude Fable 5, both new models require 30-day data retention and are not available under zero data retention unless Anthropic expressly authorizes it, which affects teams with ZDR agreements.

LLMs

Read Anthropic's release notes

https://platform.claude.com/docs/en/release-notes/overview#september-1-2026

Summaries of vendors' own notes. Product names and logos belong to their owners; logos via logo.dev.

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