Every dashboard was green while my agent made things up. Here is how I debugged it.

A user asked our support agent how to reset two-factor auth, and it confidently walked them through steps that do not exist in our product. Made up, start to finish, but well-written and plausible.

I went to check what broke, and every dashboard was green. The request returned a 200. Latency was normal. The error rate had not moved. As far as our monitoring was concerned, nothing had happened at all.

That is the thing about agent bugs. The worst ones do not throw. They return a clean, confident, wrong answer, and your normal tools call that a success. Here is how I actually track these down now, without a single line of code in this post.

Why your normal monitoring cannot see this

A regular monitoring stack treats the whole agent as one HTTP call. It sees the request go in, the response come out, and a 200 in between. It has no idea that inside that one call the agent did a retrieval, made two model calls, and picked a tool.