Function Calling

Function calling is the specific implementation of tool use where the language model emits a structured JSON object matching a function signature, which the host application then executes.

What is Function Calling?

Function calling is the dominant API pattern for tool use across major model providers. The developer registers function schemas; the model returns a function name and arguments; the application validates and executes them; the result is fed back to the model. Function calling allows strict schema enforcement, type validation, and clean separation between model output and side effects. It is the safest way to let an LLM trigger real-world actions.

How does Function Calling apply to enterprise AI?

Function calling is used in enterprise voice agents, customer support automation, internal copilots, and any workflow where AI must read or write to a system of record.