29th September 2025 Anthropic released Claude Sonnet 4.5 today, with a very bold set of claims: Claude Sonnet 4.5 is the best coding model in the world. It’s the strongest model for building complex agents. It’s the best model at using computers. And it shows substantial gains in reasoning and math. Anthropic gave me access to a preview version of a “new model” over the weekend which turned out to be Sonnet 4.5. My initial impressions were that it felt like a better model for code than GPT-5-Cod...