Claude Mythos Preview

Invitation-only research preview model for defensive cybersecurity workflows under Project Glasswing (no self-serve sign-up). Recommended migration to Claude Mythos 5 (claude-mythos-5). Standalone per-model pricing not published on the pricing page (Long context note groups it with the 1M-context models at standard pricing, but no $ figures listed) -> prices null. Included in 1M-token context group. Max output / knowledge cutoff not published (null). DEPRECATION DATE ADDED 2026-09-19 AS A CORRECTION OF OUR OWN OMISSION, NOT AS A PROVIDER EVENT: Anthropic's "Current and recently retired models" table carries this row as "claude-mythos-preview | Deprecated | June 9, 2026 | To be announced" (columns: API model name, Current state, Deprecated, Tentative retirement date), read first-hand from the raw HTML of the deprecations page today, and this catalog was publishing deprecated_on null against a date the provider states as data. Until 2026-09-19 this note said the model was "absent from the Current and recently retired models table where every dated Anthropic model appears" - that was read on 2026-09-02 and is not what the page shows now; whether Anthropic added the row since or the earlier read missed it cannot be established from the live page, so the claim is withdrawn rather than re-stated. retires_on STAYS NULL, and now on a literal rather than on an absence: the retirement cell reads "To be announced", and that column is labelled "Tentative retirement date" in any case. Until 2026-09-02 this row carried retires_on 2026-06-30, read from the deprecations page on 2026-06-28; Anthropic has withdrawn that date, and publishing a past one would tell a consumer this endpoint is dead while Anthropic still lists it. Status stays "deprecated", which is the state the provider's own cell declares.

Source: Anthropic official documentation ↗

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