On November 9, U.S. local time, Anthropic released Claude Fable5.2 and Mythos5.2. The two share the same underlying model and focus on coding, reasoning, and vision capabilities. Fable is open to a broad range of users, while Mythos is limited to vetted organizations.
Fable5.2 coordinated more than 1,000 sub-agents working continuously for 8 days. Starting from an empty folder, it wrote an operating system prototype that can boot on a laptop, complete with a kernel, disk and keyboard drivers, file storage, windows, and a login screen. It also converted the proof of Fermat's Last Theorem into a Lean formal proof that can be checked step by step in 30 hours; the earlier research version of Claude needed 11 days and relied on human guidance.
Matthew Berman's team used Fable to build custom photo-editing and video-editing tools and canceled its Adobe subscription. Working with Diode, they had the model design a home voice assistant, a USB hands-free calling device, and a handheld electronic pet. The circuit board design was ready to send to a factory within one day, and assembly succeeded immediately. The model also controlled a robotic arm to solve a Rubik's Cube. In the RoboDojo Sim dual-arm test, it scored 64.9%, higher than Fable5.1's 27.6% and GPT-6Astra's 29.8%.
