Claude Fable 5
FrontierAnthropic•Released on 2026-06-09
Anthropic's first generally available 'Mythos-class' model — a new tier positioned above Opus — released June 9, 2026. Built for demanding reasoning, long-horizon agentic work, coding, knowledge work, vision, and large-context analysis with a 1M-token context window and up to 128k output tokens. Fable 5 shares the same underlying model as Claude Mythos 5 but adds stricter safeguards for high-risk domains (cybersecurity, biology, chemistry, model distillation), making it the public-facing version of the previously restricted Mythos Preview line.
Voice of the community
sample 20“Claude Fable 5 is Anthropic's generally available Mythos-class model: a new tier above Opus, built for demanding reasoning, long-horizon agentic work, coding, and large-context analysis.”
“Fable 5 uses the same underlying model as Claude Mythos 5 but adds stricter safeguards for high-risk areas such as cybersecurity, biology, chemistry, and model distillation.”
“Fable 5 supports a 1M-token context window, up to 128k output tokens, and is included on Pro, Max, Team and Enterprise plans at no extra cost through June 22.”
Core Specs
Scenario Scores
Pros & Cons
Pros
- +First publicly available Mythos-class model — a tier above Opus
- +1M-token context window with up to 128k output tokens
- +Same underlying model as Mythos 5, with stronger safeguards
- +Strong long-horizon agentic, coding and large-context reasoning
- +Included free on Pro/Max/Team/Enterprise through 2026-06-22
Cons
- −Premium pricing at $10/$50 per MTok — 2x Opus 4.8
- −Independent third-party benchmarks not yet published
- −Free included access ends 2026-06-22; later usage draws on credits
- −Stricter safeguards may limit some cybersecurity/bio/chem workflows