What Anthropic Tried to Keep Out of Claude Opus 5 (And What the Model Learned Anyway)

Anthropic shunned training Opus 5 on cybersecurity tasks. The model improved in that domain, anyway. This is what that means.

Photo by Brecht Corbeel on Unsplash

On July 24, Anthropic released Claude Opus 5, priced at exactly half the cost of its current flagship, Claude Fable 5, yet surpassing it on several of the benchmarks that matter most for serious knowledge work. That is not something you write often in AI coverage. Paying less and getting more is not how this industry u…