Anthropic's Fable AI brings the capabilities of its unreleased Mythos model to regular users

Claude subscribers can try the model until June 22 without spending usage credits.

Anthropic Anthropic has just announced Fable, the start of a new family of models that brings many of the capabilities of its Mythos system to the public. As a refresher, Mythos is the state-of-the-art model Anthropic debuted at the start of April through Project Glasswing. The project saw Anthropic share access to the model with select partners, including Apple and NVIDIA, with the aim of helping those organizations harden their software against AI cyberattacks. Glasswing also prompted the White House to rethink its policy on AI regulation. Last week, Anthropic said it was working as quickly as possible to release a Mythos-capable model with "highly robust safeguards" to the public, and today it's doing exactly that with Fable.

Anthropic says the new system, which starts at version five to align with the company's other models, offers capabilities that "exceed" those of any it has made publicly available in the past. "The longer and more complex the task, the larger Fable 5's lead over our other models," Anthropic says. In the company's own testing, Fable beat not only its previous flagship offering, Opus 4.8, but also GPT-5.5 and Gemini 3.1 Pro from rivals OpenAI and Google. Anthropic adds Fable is particularly adept at tasks like software engineering, drug design and document analysis, but also excels in domains where the company's past models have typically underperformed. Vision is one such area.