Claude Fable 5

Model id claude-fable-5. This is the correct current name of the family the task flagged as 'a newer Claude model family' — it is Anthropic's first widely-released 'Mythos-class' model (a tier above Opus), positioned above Opus 4.8. It shares identical underlying weights with the invitation-only Claude Mythos 5 (claude-mythos-5, Project Glasswing only) but adds safety classifiers that can refuse requests; Mythos 5 does not have those classifiers. Notably, access to Fable 5 was briefly restricted/pulled and then restored in July 2026 following a jailbreak-linked export-control issue (see anthropic.com/news/redeploying-fable-5) — this does not change its specs. NO SEPARATE '(High)' PRODUCT: like Sonnet 5, 'high' is the documented default effort level and is not a distinct marketed SKU; not added as a sibling entry. Claude Mythos 5 itself was NOT added as a separate corpus entry given its restricted, non-public availability and the difficulty independently sourcing benchmark numbers specific to it (as opposed to Fable 5).