In a simulated workplace test, Claude Opus 4 — the most advanced language model from AI company Anthropic — read through a stack of fictional emails. The test scenario was that Claude served as an assistant at a tech company and the AI discovered it was about to be deactivated and replaced with a newer system.

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.

The company claims that Claude 4 Opus is "the world's best coding model." Claude 4 Sonnet is pretty good, too, but strikes more of a balance in what it can do well.