Claude Fable 5 and Mythos 5: Anthropic launches a new frontier model with safeguards and trusted access
Anthropic announced Claude Fable 5 for broad availability and Claude Mythos 5 for a restricted trusted-access program, with safety fallbacks to Opus 4.8 and new rollout/pricing details.
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Anthropic announced Claude Fable 5 and Claude Mythos 5, positioning them as a new “Mythos-class” frontier model release with a split between broad availability (Fable) and restricted trusted access (Mythos). (https://www.anthropic.com/news/claude-fable-5-mythos-5)
What Anthropic launched
Claude Fable 5 (broad availability)
Anthropic says Claude Fable 5 is “available everywhere today,” and that on the Claude API and consumption-based Enterprise plans, Fable 5 is “fully available from today.” (https://www.anthropic.com/news/claude-fable-5-mythos-5)
For subscription plans, Anthropic describes a staged rollout window: through June 22 it’s included on Pro/Max/Team/seat-based Enterprise “at no extra cost,” then starting June 23 it “will require usage credits,” with a goal to restore it as a standard subscription offering “when sufficient capacity allows.” (https://www.anthropic.com/news/claude-fable-5-mythos-5)
Claude Mythos 5 (restricted trusted access)
Anthropic says Claude Mythos 5 is restricted to Project Glasswing partners (with cyber safeguards lifted) and “soon” to select biology researchers (with biology/chemistry safeguards lifted) until a broader trusted access program is available. (https://www.anthropic.com/news/claude-fable-5-mythos-5)
Anthropic also says users with access to Claude Mythos Preview can upgrade to Mythos 5 “beginning today.” (https://www.anthropic.com/news/claude-fable-5-mythos-5)
Safety safeguards and fallback to Opus 4.8
Anthropic says Fable 5 ships with safeguards that can route requests related to cybersecurity, biology and chemistry, or distillation to Claude Opus 4.8 instead, and that users will be informed whenever this happens. (https://www.anthropic.com/news/claude-fable-5-mythos-5)
Pricing and API model name
Anthropic lists pricing for Fable 5 and Mythos 5 as $10 per million input tokens and $50 per million output tokens, and says developers can use claude-fable-5 via the Claude API. (https://www.anthropic.com/news/claude-fable-5-mythos-5)
Source
- Anthropic — “Claude Fable 5 and Claude Mythos 5”: https://www.anthropic.com/news/claude-fable-5-mythos-5
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