Anthropic launched Claude Sonnet 5 on June 30, 2026, positioning the mid-tier model as a lower-cost alternative to its own Opus 4.8 as well as OpenAI’s GPT-5.5 and Gemini 3.1 Pro. The model is now the default for free and Pro plans and is available across every subscription tier.
Sonnet 5 is priced at $2 per million input tokens and $10 per million output tokens through August 31, 2026, after which input token pricing rises to $3 per million. Anthropic says the model delivers performance close to Opus 4.8 at a significantly lower cost, though Gemini 3.5 Flash remains cheaper.
The model is designed for agentic tasks — work that requires planning, tool use, and autonomous execution with minimal human input. On an agentic coding benchmark, Sonnet 5 scores 63.2%, compared to 58.1% for its predecessor Sonnet 4.6 and 69.2% for Opus 4.8. On a knowledge work benchmark, Sonnet 5 slightly outperforms Opus 4.8. Anthropic says the model can also check its own output without being explicitly prompted to do so.
Zapier senior engineer Daniel Shepard said in a statement that Sonnet 5 completed a two-part Salesforce automation task end to end — updating account tiers and sending a launch announcement — where earlier versions had stalled midway.
On safety, Sonnet 5 shows a lower rate of undesirable behaviors than Sonnet 4.6, including reduced hallucination, less sycophancy, and better resistance to prompt injection attacks. However, Anthropic notes it does not match Opus 4.8 or Claude Mythos Preview on misaligned behavior, and has a lower ability to perform dangerous cybersecurity tasks than current Opus models.
The release reflects a broader shift in the foundation model market, where Anthropic says agentic capability is now an expectation at every price tier, with cost and reliability becoming the primary differentiators among competing models.
Source: TechCrunch