Key Takeaways
Anthropic’s Claude Fable 5 launches at $10 per million enter tokens, chopping Mythos Preview pricing by greater than 50%.Stripe compressed 2+ months of engineering work into 1 day utilizing Fable 5 on a 50-million-line Ruby codebase.Fable 5 is free on Professional and Group plans by means of June 22, after which utilization credit can be required by Anthropic.
What Claude Fable 5 Is
Fable 5 is Anthropic’s most succesful publicly obtainable mannequin. In Tuesday’s launch, the corporate says it leads on practically all examined AI benchmarks, with explicit energy in software program engineering, data work, scientific analysis, and long-context duties. Anthropic notes that the longer and extra complicated a process, the bigger Fable 5’s benefit over its earlier fashions.
Pricing is ready at $10 per million enter tokens and $50 per million output tokens. That’s lower than half the price of Claude Mythos Preview. Builders can entry the mannequin by means of the Claude API utilizing the string claude-fable-5.
Early Testing Outcomes
The numbers from early testers are particular. Stripe reported that Fable 5 compressed months of engineering work into days, finishing a codebase-wide migration throughout a 50-million-line Ruby codebase in a single day. The identical process would have required a full engineering crew greater than two months to complete by hand.
IMC mentioned Fable 5 handed their buying and selling evaluation evaluations throughout factual lookup, conceptual reasoning, root-cause evaluation, and expected-value evaluation. On Hebbia’s Finance Benchmark for senior-level reasoning, Fable 5 scored highest amongst all examined fashions.
On frontier physics analysis, one companion reported Fable 5 reached practically the identical outcome as GPT-5.5 after 36 hours, utilizing roughly a 3rd of the reasoning tokens. GPT-5.5 required 4 days to achieve a comparable outcome.
Imaginative and prescient and Lengthy-Context Positive factors
Fable 5 accomplished the online game Pokémon FireRed utilizing solely uncooked sport screenshots, with no maps, navigation aids, or further instruments. Earlier Claude fashions required a extra complicated helper setup to play the identical sport.
On reminiscence and long-context duties, Anthropic mentioned file-based reminiscence improved Fable 5’s efficiency on the deck-building sport Slay the Spire 3 times greater than it improved Opus 4.8 beneath the identical situations.
Mythos 5 and Cybersecurity
Anthropic additionally launched Claude Mythos 5, constructed on the identical underlying mannequin as Fable 5 with sure cybersecurity safeguards lifted. Mythos 5 is being deployed by means of Venture Glasswing, a collaboration with the U.S. authorities, as an improve to Claude Mythos Preview. Anthropic describes it as carrying the strongest cybersecurity capabilities of any AI mannequin at present obtainable.
Safeguards and Availability
Fable 5 contains classifiers that redirect requests touching cybersecurity, biology and chemistry, or mannequin distillation to Claude Opus 4.8 quite than refusing outright. Anthropic says greater than 95% of classes set off no fallback in any respect.
A brand new 30-day knowledge retention coverage applies to all Mythos-class mannequin visitors. Anthropic says the information is not going to be used for mannequin coaching and can be deleted after 30 days in practically all instances.
Fable 5 is on the market now on Professional, Max, Group, and Enterprise plans at no additional price by means of June 22. On June 23, utilization credit can be required. Anthropic mentioned it intends to revive Fable 5 as a part of customary subscription plans as soon as capability permits.
Individually, Anthropic filed confidentially for an preliminary public providing in latest weeks. OpenAI adopted with the same submitting shortly after. Each developments arrived in opposition to a backdrop of continued promoting stress on AI, semiconductor, and mega-cap tech shares on Wall Avenue.
