Anthropic launches Claude Sonnet 5 as a cheaper way to run agents

Anthropic released Claude Sonnet 5 on Tuesday, a midsize model the company said is designed to run agentic tasks at lower cost than larger models. The new model can make plans, use tools like browsers and terminals, and run autonomously at levels that previously required larger and more expensive models, Anthropic said in a blog post, according to TechCrunch. Sonnet 5 is priced at $2 per million input tokens and $10 per million output tokens through Aug. 31, after which the price rises to $3 per million input tokens and $15 per million output tokens. That makes it cheaper than Anthropic's Opus 4.8, OpenAI's GPT-5.5 and Google's Gemini 3.1 Pro, but more expensive than Gemini 3.5 Flash. Sonnet 5 became the default model for free and Pro plans as of Tuesday. The model shows improvements over its predecessor, Sonnet 4.6, on agentic coding, tool use, reasoning and knowledge work, according to Anthropic. On a coding benchmark, Sonnet 5 scored 63.2% compared to Opus 4.8's 69.2% and Sonnet 4.6's 58.1%. On a knowledge work benchmark, Sonnet 5 slightly outperformed Opus 4.8. Anthropic said Sonnet 5 has lower rates of undesirable behaviors and hallucinations than Sonnet 4.6. The story was reported by Rebecca Bellan of TechCrunch.