Mythos vs Opus: Tier and Access, Side by Side
| Spec | Claude Mythos 5 | Claude Opus 4.8 |
|---|---|---|
| Tier | Mythos-class (above Opus) | Opus |
| Availability (general) | Suspended — Glasswing only ↗ | Available |
| Released | June 9, 2026 ↗ | — |
| Context window | 1M tokens | 1M tokens unofficial |
| Max output | Up to 128k tokens | Up to 64k tokens unofficial |
| Input price (per M tokens) | $10 / M (reference) | $5 / M |
| Output price (per M tokens) | $50 / M (reference) | $25 / M |
| Data retention | 30 days | — |
| Zero-data-retention (ZDR) | No ZDR | — |
| Covered Model | Yes — Covered Model | — |
| Safeguards | Classifiers lifted (vs Fable 5) | — |
| How to access | Project Glasswing only | Claude API, apps, cloud marketplaces |
Two different products, not two tiers of the same thing
Mythos 5 is the unmediated, Glasswing-only edition of the June 2026 Mythos-class release. Opus 4.8 is the general-availability flagship. Mythos 5 is the higher tier with a 1M-token context and $10/$50 Glasswing pricing (the public Preview ran nearer $25/$125), while Opus 4.8 is $5/$25 and reachable by anyone with API access.
Access is the real divide
The defining difference isn't a benchmark — it's who can run it. Mythos 5 requires Project Glasswing vetting, and even qualified participants are affected by the June 12, 2026 export-control suspension. Opus 4.8 has no such gate. So while Mythos 5 is nominally more capable and runs without classifier fallback, that capability is unavailable to the general public.
Bottom line
If you're building outside Glasswing, Opus 4.8 is your flagship, full stop. If you're a vetted Glasswing organization with a genuine need for the unmediated model, Mythos 5 is the reason the program exists — subject to current restrictions.
Caveat
Cross-model performance claims are unofficial until the system card. Decide on access eligibility and price, not on circulating numbers.
Frequently asked questions
Can I get Mythos without Glasswing?
No. Mythos 5 is restricted to approved Project Glasswing participants. The general-availability flagship is Opus 4.8.
Is Mythos worth the higher price over Opus?
Only if you specifically need the unmediated, classifier-free model and qualify for Glasswing. Otherwise Opus 4.8 delivers flagship capability for less.
Why can't I access Mythos right now?
Beyond the Glasswing gate, access is suspended under a US export-control directive issued June 12, 2026.
Sources & further reading
- Anthropic — Fable & Mythos access noticeOfficialanthropic.com
- anthropicmythos.aiFlagshipanthropicmythos.ai
Facts on this page link to their source. Quotes are kept under 15 words and attributed; figures labelled unofficial are third-party until Anthropic publishes system-card numbers.