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Function Calling, End to End Explained

Function calling is a round trip with strict roles: you describe tools with JSON Schema, the model decides when to call one, YOUR code executes it, and the result goes back to the model to finish the answer. The schema is the contract.

Animated diagrams · 2 flows

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One Tool Round-TripApp ↔ model ↔ tool, then back againYes — one loop per callTwo model turns + your tool's runtimeProvider tool-use APIMedium — schemas + plumbingGrounding answers in live data and real actions
The Schema Is the ContractCall arguments → schema validationYes — every call validatedMicroseconds of validationYour validation layerOne schema per toolSafe tool boundaries and typed integrations