Anthropic releases Claude Sonnet 5.5

Anthropic released Claude Sonnet 5.5, the second model in its 5.5 family after Opus 5.5. The company says the new Sonnet runs more than 30 percent faster and costs up to 30 percent less for most work.

Anthropic positions the model for everyday coding, bug fixing and document creation rather than the most judgement-heavy work reserved for Opus. It reports a 70.6 percent score on Terminal-Bench 4.0, compared with 10.3 percent for Sonnet 5, and says Sonnet 5.5 finishes two points behind Opus 5.5 on GDPval-AA.

Benchmark gains this large can reflect both model changes and the surrounding agent harness. The more durable product change is the combination of lower cost and higher speed, which affects every repeated task even when benchmark performance is not representative.