tl;dr: Anthropic released Claude Opus 5, claiming state-of-the-art performance on coding and knowledge-work benchmarks (Frontier-Bench, GDPval-AA, ARC-AGI 3, OSWorld 2.0) at half the cost of their top-tier "Fable 5" model, though it still trails "Mythos 5" on cybersecurity exploit development and advanced biology tasks. Pricing matches Opus 4.8 at $5/$25 per million input/output tokens, and Anthropic is loosening cyber safeguards (blocking ~85% less often than Fable 5) while adding beta features like mid-conversation tool changes and automatic model fallbacks for flagged requests.