Claude Mythos 5.1
Anthropic · Sorti sept. 2026
Same weights as Claude Fable 5.1 at the same $10/$50 rate, with cyber and life-sciences safeguards loosened for vetted users. The catch is access: Mythos 5.1 ships only through Anthropic's trusted-access programs (Cyber Verification and Life Sciences Verification), so there is no self-serve API and no way to buy your way in. Conditional for the same reason as Mythos 5: elite capability behind a vetting gate. Everyone else should use Fable 5.1.
Est-ce fait pour vous ?
Recommandé pour
- Vulnerability discovery and offensive-security research — cyber safeguards are loosened relative to Fable 5.1
- Agentic terminal work at the frontier: 60.9% Terminal-Bench 4.0, 5.1 points above Fable 5.1
- Life-sciences work that trips Fable 5.1's biology classifiers, for organizations inside the Life Sciences Verification Program
Déconseillé pour
- Any team not admitted to a verification program — there is no public API and no self-serve path
- General coding and knowledge work — identical price, identical weights, and Fable 5.1 is the one you can actually call
- Organizations outside the US — Anthropic says access is currently limited to a set of US organizations, with international expansion coordinated with the US government but undated
Performances par tâche
Cybersecurity research
Loosened cyber safeguards on frontier weights; the reason the model exists
Agentic coding
60.9% Terminal-Bench 4.0, the highest published score in the 5.1 release
General knowledge work
Same weights as Fable 5.1, but no published index scores and no reason to prefer it here
Tarifs
Entrée
$10 / 1M tokens
Sortie
$50 / 1M tokens
Contexte
1M context, $0.25/1M cache; vetted access
Tests de performance
| Test | Score | Source |
|---|---|---|
| Terminal-Bench 4.0 | 60.9% | Source |
Aucun changement de verdict pour l’instant
L’horloge tourne dès le premier jour : les changements apparaîtront ici à mesure que notre verdict évolue.
Sources
Journal de vérification
Aucune vérification pour le moment
Nous n’avons pas encore enregistré de vérification pour cette entrée. Dès qu’une vérification s’exécute, son historique apparaît ici.