How to Monitor Your AI Agent: Costs, Errors & Performance (2026 Guide)

How to Monitor Your AI Agent: Costs, Errors & Performance (2026 Guide) — Paxrel - [Paxrel](/) [Blog](/blog.html) # How to Monitor Your AI Agent: Costs, Errors & Performance (2026 Guide) Photo by Tima Miroshnichenko on Pexels March 25, 2026 · 12 min read You ship an AI agent. It runs. At first, everything looks fine. Then, three weeks later, you check your API bill and it's 8x what you budgeted. Or a user reports a problem and you realize the agent has been silently hallucinating details for days. Or the pipeline is stalling somewhere and nobody noticed because there was no alert. This is the unsexy side of AI agents that almost nobody talks about: **monitoring**. Building the agent is the exciting part. Keeping it working correctly, cheaply, and reliably once it's live is where most teams fail. This guide covers the 4 pillars of AI agent monitoring, practical Python setups for each, a comparison of the main observability tools, and the exact metrics and alert thresholds we use at Paxre