Tool Calling

You might say

AI can talk, but how do I get it to actually check the database or make a request?

A model’s request for an application to run a named tool with parametersA model can request a calendar lookup, but the application must validate the permissions and parameters before it reads the schedule. The returned result, not the request text, proves what happened.

Know first

Structured Output API

Function Calling

From “check tomorrow afternoon” to a calendar result

Tomorrow

13:00 Project meeting15:00 Free16:00 Review17:30 Free

User asks

Can you check whether I’m free tomorrow afternoon?

How a tool request becomes a real result

The model requests a tool: A tool call names a tool and supplies parameters; it does not enter the calendar itself.

The product validates: It checks whether the tool is allowed, whether parameters make sense, and whether the user has access.

A real result returns: Only the executed result comes back for the model to explain.

Quick checkChoose the best answer

An agent says a calendar meeting is created but has not run the calendar tool. What is the accurate state?

A meeting title in model text means the meeting existsTell the user it worked without waiting for the tool responseIt has only requested a tool call; claim creation only after the app executes it and returns a result

You can say this to an AI Agent

Validate meeting creation with a mock or dedicated test calendar, not a real schedule. Show the proposed time, attendees, and title before the call; simulate one success and one permission denial, reporting only from the actual tool result. Delete any event created in the test calendar afterward.

Learn next

1ReAct→2Agent Loop→3Structured Output→

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