Silent failures become the most common way agents fail as they get better, and nothing in your monitoring catches them.
By then an engineer has spent hours in the logs, only to find the same failure across hundreds of conversations, running for weeks. The tools you have weren't built to catch it.
Great for debugging a single trace. Turning 50,000 of them into a trend takes days.
They catch the failures you thought of. The costly ones are the failures you didn't.
Ask an LLM which step caused a failure and it's right about 14% of the time.
Returns 200, finishes, still wrong. A benchmark's success score was off by half until someone read the logs.