Overview
Claude Sonnet is anthropic’s mid-tier Claude model line for balanced reasoning, coding, and agentic workloads. Current generation: claude-sonnet-5 (successor to claude-sonnet-4-6). Haiku 5.5 launch (Oct 2026) also cut Sonnet 5.5 cache-read pricing (2026-10-07-anthropic-claude-haiku-5-5).