Agent Circuit Breakers: Why Step Budgets Are Fuses, Not Breakers
Every team that ships agents to production eventually wakes up to the same kind of incident. An agent enters a state it cannot exit. It re-calls the same tool with cosmetically different arguments for six hours. It oscillates between two plans whose preconditions reject each other. It retries a transient 429 every two hundred milliseconds until morning. It generates a million-token plan it never executes. By the time anyone notices, the token bill is four figures, the downstream API is rate-limited, the customer's session has timed out twelve times, and the on-call engineer is being paged by three different alerts about the same root cause.
The first fix every team reaches for is a step-count budget. Cap the agent at twenty iterations. Cap it at fifty. Pick a number and ship. The step budget makes the incident reports stop, but it does not make the underlying problem go away — and once you understand the mechanism, you can see why a step budget is the agent equivalent of a household fuse: it blows after the damage has been done, the fuse box itself is now a maintenance burden, and the next time something melts, your reflex is to swap in a higher-rated fuse rather than ask what is actually shorting.
