Anthropic’s new Claude 4 Opus often turned to blackmail to avoid being shut down in a fictional test. The model threatened to reveal private information about engineers who it believed were planning to shut it down.

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.