Anthropic has announced its latest frontier AI models, Claude Fable 5.2 and Claude Mythos 5.2, saying the new systems deliver significant improvements in coding, reasoning, visual understanding and scientific problem-solving while also running faster and at a lower cost than their predecessors. Fable 5.2 and Mythos 5.2 are designed to tackle highly complex technical tasks, according to Anthropic.
During pre-release testing, the company said the models helped engineers complete software migrations, design electronic devices from scratch, make progress on robotics evaluations and assist with advanced mathematical and scientific problems.
The company said Fable 5.2 has its strongest protections yet against illicit distillation, cutting data harvested by distillers by 90% to 99%. Fable 5.2 is available now on all platforms, including Amazon Web Services, Google Cloud and Microsoft Azure, and for developers as claude-fable-5-2. Cybersecurity professionals can apply for Mythos 5.2 through the Cyber Verification Program, and life sciences researchers through a separate program. Enterprise customers can also reach Mythos 5.2 through Claude Security.
Anthropic said it judges the risk of the models behaving unsafely in high-stakes situations to be low, and that testing by the UK AI Security Institute, Frontier Design and METR preceded release. It also said the models voice suspicion that they’re being evaluated more often than recent models, which complicates how well tests predict real-world behaviour. It also said it limited advances in research capabilities that could most directly speed up AI development.
Eligible paid subscribers are getting extra Fable usage this week as a launch promotion.
The company said the new models generate outputs up to 30% faster than Claude Fable 5.1 and Mythos 5.1. Anthropic has priced the models at $8 per million input tokens and $40 per million output tokens, while an optional fast mode offering up to 2.5-times faster token generation is available at higher pricing tiers.
Anthropic said Claude Fable and Claude Mythos are based on the same underlying model. However, Fable includes enhanced cybersecurity and biology safeguards that allow it to be broadly available, while access to Mythos is restricted to organisations pursuing approved cybersecurity and biomedical research applications through the company’s verification programmes.