Released: July 2026. Vendor: Anthropic. Model string: claude-sonnet-5.

What changed: stronger performance on long-running coding tasks, improved tool use, and better debugging behaviour, shipped at a lower price than the tier it replaces.

Who it affects: anyone running agentic coding workflows, long tool-use chains, or multi-step automation where the model must hold context across many turns.

Action required: none. Existing integrations continue to work; switching is a model-string change.