Claude Sonnet 5.5 keeps Sonnet 5 pricing but changes thinking, tool choice, computer use, conversation replay, and response handling. Test these six issues before switching production traffic.
Anthropic launched Claude Sonnet 5 with lower launch pricing, stronger agentic behavior, Claude Code support, and broad availability across Claude plans. For developers, the useful question is not whether it is the flashiest Claude model, but whether its cost, context window, and migration changes make long-running agents easier to put into production.