What is Function calling schema?

The JSON schema that defines a tool's name, description, and expected inputs — what the model reads to decide when and how to call it.

How it works

The model never sees your code, only the schema. A precise name, a clear description, and strict parameter types are what make a tool callable reliably. Vague schemas produce wrong or hallucinated calls.

Example

In practiceYou define search with a required string 'query' and an optional integer 'max_results'; the model fills them correctly because the schema is explicit.

Why does my tool get called wrong?

Usually a vague description or loose schema. Make the name and description say exactly what it does and constrain the inputs.

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