Claude Sonnet 5

Anthropic's most agentic Sonnet yet (July 2026); narrows the gap to Opus 4.8 at lower price via effort-level cost-performance tuning; 1.0–1.35× tokenizer inflation; safer than Sonnet 4.6 on the behavioral audit but weaker cyber than Opus; ships default real-time cyber safeguards; and on the first third-party per-task bench costs *more* than Opus 4.8 per task ($2.09 vs $1.94) at lower success (81% vs 87%) despite ~1.7× cheaper tokens