Choose Fable 5
You need public access, strong agentic capability, and a documented API path today.
Model comparison
Claude Fable 5 vs Mythos 5
Fable 5 is the generally available path. Mythos 5 is limited availability. Opus 4.8 remains important for fallback and cost-sensitive work.
Short comparison
ModelAvailabilitySafeguardsBest fit
Fable 5Generally availablePublic safeguards and fallbackAdvanced public reasoning and agents
Mythos 5Limited availabilityFewer public restrictionsApproved high-trust customers
Opus 4.8Generally availableStandard Claude safety behaviorFallback and lower-cost premium tasks
Main difference
The practical split is not hype. It is access and risk controls.
Anthropic describes Fable 5 as sharing the same underlying model as Mythos 5 while adding robust safeguards for public use. That means most searchers should evaluate Fable 5 first, because it is the model they can actually access.
Fable 5Public model
Mythos 5Project Glasswing
Shared pricing$10 in / $50 out
FallbackOpus 4.8
Decision rule
Choose Opus 4.8
You need lower costs, mature behavior, or a fallback target when a Fable request is declined or routed.
Ask about Mythos 5
You are an approved organization with a legitimate high-trust need and a direct account-team path.
FAQ
Quick answers
Which model is public?
Claude Fable 5 is generally available. Claude Mythos 5 is limited availability through Project Glasswing or account-team access.
Do Fable 5 and Mythos 5 have the same pricing?
Anthropic's introduction page says Fable 5 and Mythos 5 share the same specs and pricing.
Why does Opus 4.8 matter?
Anthropic describes Fable safeguards that route certain sensitive cybersecurity and biology requests to Opus 4.8.
Should I try to get Mythos 5 access?
Most users should start with Fable 5. Mythos 5 access is for approved customers and trusted access programs.
Sources
Checked June 11, 2026
Model availability, pricing, and safeguard behavior can change. This guide links to primary sources so the page can be refreshed quickly.