Agent loops are eating your API budget

Everyone's shipping agents right now. ReAct, tool-calling loops, whatever. Looks great in demos. But nobody mentions the billing dashboard the morning after. Agent loops are entirely unpredictable. A simple task might take 2 LLM calls. Or the model gets confused, tries a failing tool 20 times, and burns 40 calls before timing out. Local test: $0.05. Prod: user triggers a loop, agent hallucinates, costs $4 for a single request. Multiply by 100 users. Devs treat LLM calls like standard API calls. They aren't. They're variable-cost compute disguised as a REST endpoint. If you run agents in prod, you need defensive monitoring: Hard iteration caps. Never let an agent run "until complete". max_iterations=5. Return an error instead of a massive bill. Per-tenant attribution. Global tracking is useless. When your Anthropic usage spikes 300%, you need to know exactly which userId caused it so you can rate-limit them. Budget alerts. Set up webhooks that fire the second a user crosses their daily