Claude 4 Sonnet is a leaner model, with improvements built on Anthropic's Claude 3.7 Sonnet model. The 3.7 model often had problems with overeagerness and sometimes did more than the person asked it to do, Amodei said. While it's a less resource-intensive model, it still performs well, he said.

Artificial intelligence startup Anthropic says its new AI model can work for nearly seven hours continuously, further signaling AI’s growing presence in the workplace.

Anthropic released its latest Claude 4 models — Claude Opus 4 and Claude Sonnet 4 — but Windsurf users were not given immediate access. Varun Mohan, co-founder of Windsurf, said in a post on X, “Unfortunately, Anthropic did not provide our users direct access to Claude Sonnet 4 and Opus 4 on day one.”