Lesson 3: When tools fail: retries, limits and handing over
30 min read·13 Oct 2026
Module 3 · Lesson 3 · About 60 minutes · Needs: Lesson 1 (run_tool, actionable errors) and Lesson 2 (make_retry_safe_tools)
The situation
It is Friday 1 May 2026, week 3, the afternoon after the tool review. Dev has one more worry. "My payment service drops requests a few times a day, and the email gateway is sometimes slow. What does your agent do then?"
You trace R-1004. Mei Tanaka wants to cancel order 8204, the SoundPod wireless headphones, $79.00, still processing. The right run is three writes: cancel, refund $79.00 at once, email Mei. This lesson breaks the middle step in each of Dev's ways, and makes the tools fail safely and visibly.