Anthropic ships a new mid-tier Claude, claiming a big coding leap
The mid-tier model nears flagship scores at unchanged prices, but every number is Anthropic's own test — and it lands right before OpenAI's DevDay.
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Anthropic released Claude Sonnet 5.5 on September 28, positioning it as the mid-tier model below Opus 5.5, with claimed speed gains of 30%+ and per-task costs up to 30% lower.
The headline number on Anthropic's page: a score of 70.6% on the Terminal-Bench 4.0 agentic coding evaluation, versus 10.3% for the previous Sonnet 5. Prices are unchanged — $2 per million input tokens and $10 per million output tokens. It is also the first Sonnet-tier model to ship with cyber safeguards and fallbacks.
One caveat: all scores are Anthropic's own tests, and because OpenAI has not published GPT-6 Sol results, the comparison tables actually use GPT-5.6 Sol instead, weakening cross-vendor comparability. The launch lands just before OpenAI's DevDay.