Anthropic releases Sonnet 5.5, claiming 30% speed gain and lower cost

As the AI model wars continue, Anthropic has released the newest version of Sonnet, the company’s mid-tier model, which it says will work much faster (and for significantly less) than its predecessor.

The lab describes Sonnet 5.5 as an ideal assistant for everyday tasks — including coding and creating office documents.

5.5’s predecessor, Sonnet 5, was announced about three months ago. At the time, the model’s selling point was efficient agentic deployment — the ability to run agents at a lower cost than competitors.

The big selling point with 5.5, meanwhile, is speed. Anthropic claims that Sonnet 5.5 is 30 percent faster than its predecessor, and that its rate of token burn is significantly slower.

In the Anthropic hierarchy of models, Sonnet is less powerful than the Opus model, but can be more useful in certain circumstances because its agility. In particular, Anthropic’s benchmarks show Sonnet 5.5 performing better than Opus 5.5 on agentic coding, likely because of its ability to spawn multiple agents without exceeding cost limits.

Sonnet 5.5 is also said to have significant cyber capabilities, with the company claiming that it has “comparable” cyber capabilities to Opus 5. As a result, Anthropic says that 5.5 is the first Sonnet model that will be subject the same cyber safeguards that apply to Fable and Opus.

The company also plans to release a new version of Haiku — its smallest model — in the coming weeks, although it didn’t give a firm date as to when that would happen.