A system prompt is an instruction the model is asked to follow, and most of the time it does. That reliability is real, and it is easy to mistake for a control. It is not one. A prompt shapes the distribution of outputs a model tends to produce; it does not close off the outputs you told it to avoid. On the…

Most failure handling is built around the case where the system eventually gets what it wanted. Retry the call and it works the second time. Reach for the alternate tool and it returns. That branch is satisfying to design because every path on it ends in success, and it absorbs most of the attention a team gives to reliability. The…

Retrying is the most reflexive move in error handling and the least examined. Something failed, so try it again. The reflex is defensible often enough that it survives without scrutiny, and that is exactly the problem. A retry is not a neutral safety net. It is a wager that the thing which just failed will succeed if attempted again, and that wager…

Most error handling in agentic systems is built for failures that announce themselves. An exception is thrown, a non-zero status comes back, a request times out, and the surrounding code reacts. That machinery is necessary, but it defends against the least dangerous class of failure. The failure that actually corrupts an agentic pipeline is the one that raises no signal at all: a…

When an agent fails, the reflex is to ask what to do about it. Retry, fall back, escalate, alert someone. That is the wrong first question. The right one is where the failure came from, because the answer determines which of those responses has any chance of working and which of them will only waste time and money on the way to the…