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 Crew plans via June 22, after which utilization credit will probably 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 almost all examined AI benchmarks, with specific energy in software program engineering, information work, scientific analysis, and long-context duties. Anthropic notes that the longer and extra advanced a job, the bigger Fable 5’s benefit over its earlier fashions.
Pricing is about 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 via 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 job would have required a full engineering workforce greater than two months to complete by hand.
IMC stated 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 accomplice reported Fable 5 reached almost the identical end result 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 end result.
Imaginative and prescient and Lengthy-Context Positive aspects
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 advanced helper setup to play the identical sport.
On reminiscence and long-context duties, Anthropic stated file-based reminiscence improved Fable 5’s efficiency on the deck-building sport Slay the Spire thrice greater than it improved Opus 4.8 underneath 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 via Undertaking 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 presently obtainable.
Safeguards and Availability
Fable 5 contains classifiers that redirect requests touching cybersecurity, biology and chemistry, or mannequin distillation to Claude Opus 4.8 moderately than refusing outright. Anthropic says greater than 95% of classes set off no fallback in any respect.
A brand new 30-day information retention coverage applies to all Mythos-class mannequin site visitors. Anthropic says the information won’t be used for mannequin coaching and will probably be deleted after 30 days in almost all instances.
Fable 5 is accessible now on Professional, Max, Crew, and Enterprise plans at no further price via June 22. On June 23, utilization credit will probably be required. Anthropic stated it intends to revive Fable 5 as a part of commonplace subscription plans as soon as capability permits.
Individually, Anthropic filed confidentially for an preliminary public providing in current weeks. OpenAI adopted with an identical submitting shortly after. Each developments arrived towards a backdrop of continued promoting stress on AI, semiconductor, and mega-cap tech shares on Wall Road.
