Claude Mythos 5

Claude Mythos 5 is the unusual entry in the model line-up: same specifications as Claude Fable 5, same price, but not generally available. It is offered in limited availability to approved customers through Project Glasswing, scoped to defensive cybersecurity workflows.

What is different about it

Almost nothing technically — Anthropic’s documentation says it “shares Claude Fable 5’s specs and pricing.” The difference is entirely in access and intended use.

What it does not do

• No self-serve sign-up. Access is invitation-only, arranged through an Anthropic, AWS or Google Cloud account team.
• Not available on the Claude apps or Claude Code.
• Not a general-purpose upgrade over Fable 5. If you are not doing defensive security work, Fable 5 is the same model with an ordinary onboarding path.

Its predecessor is already deprecated

claude-mythos-preview is deprecated, with claude-mythos-5 as the migration target. That is worth noting on its own: a preview model that was itself invitation-only still went through a documented deprecation with a published migration guide.

Specifications

Property	Value
Claude API ID	claude-mythos-5
Context window	1M tokens
Max output	128K tokens
Pricing	$10 in / $50 out per million tokens
Availability	Limited, invitation-only

What this page does not know

Project Glasswing’s eligibility criteria, review process and terms are not documented in the pages this entry was verified against. Treat the scope description above as the documented framing, not as a complete account of who qualifies.