Frontier-class capability at Sonnet-class cost (Claude Sonnet 5)

Anthropic — Anthropic released Claude Sonnet 5, its most agentic Sonnet-class model — approaching top-tier Opus-class performance on agentic reasoning, tool use and coding at a fraction of the cost (introductory $2/$10, then $3/$15 per M tokens). Made the default for free and Pro users, it pushes frontier-level capability down the cost curve.