Claude Mythos Preview

claude-mythos-preview is deprecated. The migration target is claude-mythos-5.

Why a preview model gets its own entry

Because of what it demonstrates rather than what it does. This was an invitation-only preview model, available to a small set of approved Project Glasswing customers — and it still received a documented deprecation notice, a named replacement and a published migration guide, listed in the same table as generally available models.

That is a useful signal when you are assessing platform risk: the lifecycle process is not reserved for GA products. Anything with a model ID gets a documented exit.

What this page does not claim

Specifications, pricing and capabilities are not documented publicly for this model, and are not guessed here. It used the newer tokenizer — the pricing documentation groups it with Claude 4.7 and later on that point — and that is the extent of what the sources checked actually say.

If you have access through Project Glasswing, the migration guide is the document you need, not this page.