Function schema
Also known as: JSON schema (tools) · function definition
A function schema is the JSON-Schema definition behind a callable function: parameter names, types, constraints, and descriptions.
- The model must emit arguments that fit the schema.
- The harness validates the call against it before executing.
- It’s the typed boundary between model output and real execution.
The safety link: schemas don't just make calls *work* — they make *invalid* calls visible. Type errors and missing parameters get caught at the boundary, not inside your code.