I Monitored 10,000 AI API Calls. Here's What Went Wrong. Or: Why your AI agent will break, and what you can do about it. The uncomfortable truth about AI APIs You built an AI agent. It works. You ship it. Then at 3 AM on a Tuesday, Claude goes down. Your agent? Dead. Your users? Angry. You? Debugging in the dark. This isn't a hypothetical. It happened on May 23, 2025 — Claude suffered a major outage. Then again on June 4 . And January 29 . OpenAI had theirs too. DeepSeek, Gemini, Mistral — nobody's immune. I wanted to know: how often do AI APIs actually fail? And what breaks when they do? So I built a diagnostic tool and ran it across 20,000 real API calls. The data After analyzing 20,000 calls across multiple providers, here's what I found: Failure Type Frequency What Happens Rate limit (429) ~40% of failures "Slow down" — but your agent doesn't know how Server error (5xx) ~25% of failures Provider is down. You wait. And wait.…