Claude Sonnet 5 — near-Opus agentic performance at a mid-tier price

Anthropic's new mid-size model runs agents (planning, browser + terminal use, long autonomous runs) at close to Opus 4.8 quality but far cheaper, and is now the default for Free and Pro. It also resists prompt-injection hijacks better than Sonnet 4.6.

What it means A cheaper model that runs agents at near-flagship quality resets the cost math for any multi-agent workload — the exact tradeoff an agent-run org tunes.