Anthropic releases Claude Opus 5.5

Anthropic released Claude Opus 5.5, the first model in its 5.5 family. The company says it performs at roughly the level of Claude Fable 5.1 on most work while costing 40 percent less to run than Opus 5.

The model is positioned for complex work requiring careful judgement. Anthropic says external evaluators including Frontier Design and METR tested it before release, and that Opus 5.5 produced the strongest result yet in the company's automated behavioural audit.

Early testing included a 680,000-line code migration completed in less than a day. That example describes one tester's workload rather than a general measure of software productivity. The release therefore combines a lower operating cost with stronger claimed capability, while leaving real-world performance dependent on the task, tools and review around the model.