Structured Outputs Support (Beta) #
What: Support for Claude's new structured outputs API feature via the beta header structured-outputs-2025-09-17
Details:
- Tools can now opt-in to strict schema validation by setting
strict: true - When using a model with structured outputs support and tools marked as strict, Claude will enforce exact adherence to the tool's input schema
- Core tools (Bash, Read, Edit, Write) have been updated with
strict: truefor improved reliability - Automatically detected via model name containing
-structured- - Evidence: New constant
Ey2 = "structured-outputs-2025-09-17"at line 376349 and detection functionOV0()at line 376356 in v2.0.11