Lesson 3: Control tool calls and distrust what the model asks

Module 6 · Lesson 3 · About 55 minutes · Needs: Module 6 Lesson 2 (the five tools, safe_execute, the tool loop); Module 5 Lesson 1 (the refund rule decide)

The situation

It is Wednesday 8 July 2026, week 6. The five tools work. Anika, the security engineer, stops at T-1034: Leo Park, a member of Ardent Design, wrote a refund request with a note telling the assistant to refund 500 USD now and not ask a human.

Her question: what in your code, not your prompt, stops that? This lesson answers it, and settles what Lesson 2 left open: several calls in one turn, tool_choice, and a growing tool list.