Anthropic Launches Claude Sonnet 5 as a Cheaper Way to Run Agents

Summary

Anthropic released Claude Sonnet 5 on June 30, 2026, a midsize model positioned to deliver agentic capabilities — autonomous planning, tool use (browsers, terminals), and extended multi-step task execution — that previously required larger, more expensive frontier models. Anthropic frames the release around the claim that Sonnet 5 "finishes end to end" on complex tasks where prior mid-tier models stalled midway. It becomes the default model for free and Pro tiers effective the following Tuesday.