Function Calling

A practical example

Example: an agent asked to "reschedule the demo for Thursday" returns a function call with arguments like event_id and new_time.

Your system validates the arguments against your calendar API, executes the update, and feeds confirmation back to the model.

What to evaluate before investing

• Test how the vendor handles invalid or hallucinated arguments, such as nonexistent IDs, and whether you can enforce schemas and validation rules.
• Ask whether tool selection can be constrained per agent or workflow, limiting which functions a given agent may invoke.
• Verify observability: can you log every function call with inputs, outputs, and latency for auditing and debugging?

Limitations and tradeoffs

Function calling reliability varies by model and task complexity; ambiguous instructions or too many similar tools increase wrong selections, so workflows need guardrails, confirmation steps, and human approval for irreversible actions.