Anthropic Launches Claude Fable 5, Its First Public Mythos-Class Model

Anthropic released Claude Fable 5, its first Mythos-class model and most powerful publicly available AI. New safeguards block responses in high-risk areas like cybersecurity and biology, enabling release of a model previously deemed too dangerous. In testing, 95 percent of Fable sessions ran entirely on Fable without falling back to Opus 4.8.