Introducing Claude Opus 5

Simon Willison · Simon Willison · 24 July 2026, 23:48 ● Covered by 12 sources

Anthropic released Claude Opus 5, a new large language model that leads the Artificial Analysis leaderboard and matches Claude Opus 4.8 in price. The model demonstrated the ability to independently write a computer vision pipeline to analyze machine drawings and reconstruct 3D models when direct image viewing was unavailable. Opus 5 improved at finding cybersecurity vulnerabilities through general capability gains rather than explicit training, while Anthropic deliberately avoided training it on exploitation techniques.

Why it matters

Introducing Claude Opus 5 I've been offline kayaking with sea otters for much of today so I haven't had a chance to put Anthropic's new model Claude Opus 5 through its paces yet. The buzz is positive, and Anthropic's description of it as a "thoughtful and proactive model that comes close to the frontier intelligence of Claude Fable 5 at half the price" sounds promising. It's currently leading the Artificial Analysis leaderboard, in front of even Fable 5. It's priced the same as Opus 4.8, and continues to offer a "fast mode" at twice the cost of the base model. Based on this anecdote in the release post it sounds like it might be relentlessly proactive: On one Frontier-Bench task, Opus 5 was given a drawing of a machine part and asked to write code to rebuild it as a 3D FreeCAD model. However, in this task, the model was intentionally given no way to directly viewthe drawing. Opus 5 responded by writing its own computer vision pipeline to pull the geometry from the raw pixels, then reco