Structured outputs
API responses are guaranteed to match JSON schemas and tool definitions; beta for Sonnet 4.5 and Opus 4.1.
Structured outputs on the Claude Developer Platform guarantee API responses match your JSON schemas and tool definitions. Now in public beta for Sonnet 4.5 and Opus 4.1, this feature eliminates parsing errors and failed tool calls for production applications.
Official source
Structured outputs on the Claude Developer Platformclaude.com · published