Function Schema Design — Reliable Tool Definitions for Your LLM

I will design and implement function schemas for your LLM application — writing function descriptions that enable reliable tool selection, parameter schemas with precise type definitions and validation, parameter descriptions that guide correct argument construction, and enum constraints for parameters with finite valid values. Function schema quality is the primary determinant of function calling reliability — a function description that clearly states when to use the function (and when not to) produces reliable selection; a function with ambiguous parameter types produces incorrect argument construction; precise schemas eliminate both failure modes without any model-level change.

The design covers function description writing with usage examples and disambiguation, parameter JSON schema design with strict type definitions, parameter descriptions guiding correct argument construction, enum constraints for categorical parameters, required vs. optional parameter configuration, and function selection accuracy testing across 30+ representative queries.