Anthropic unveiled Claude Sonnet 5, its most capable Sonnet model yet, offering performance close to Opus at a reduced price. The new AI model excels in reasoning, tool use, coding, and knowledge work while running autonomously and completing complex tasks that previous Sonnet versions could not finish.

Sonnet 5 demonstrates significant improvements over Sonnet 4.6, with performance comparable to Opus 4.8. It autonomously checks its own output, refuses malicious requests more effectively, and shows reduced rates of hallucination and sycophancy. These enhancements make it suitable for demanding agentic workflows without requiring the premium Opus tier.

The model launches with aggressive pricing at $2 per million input tokens and $10 per million output tokens, increasing to $3 and $15 after August 31. Available across all subscription tiers, Sonnet 5 becomes the default for Free and Pro plans, making high-end AI capabilities more accessible to mainstream users.