Anthropic Opens Mythos Class to Everyone: Claude Fable 5 Unleashed

Claude Fable 5's public release marks a watershed moment: Mythos-class AI, once reserved for vetted security partners, is now available to any API user, forcing competitors to recalibrate performance expectations. The model's 80.3% SWE-Bench Pro score—substantially above Opus 4.8's 69.2%—establishes a new benchmark for production AI systems, while the doubled pricing ($10/$50 per million tokens) reflects the genuine capability delta. For the next two weeks, paid Claude subscribers can trial the strongest model Anthropic has shipped without additional costs, creating an unusual window for cost-free capability evaluation before standard pricing kicks in.