After a year of running AI agents on live production workflows, one practitioner has stopped using the phrase "the model got dumber." Most cases that appear to be model stupidity or hallucinations actually result from three recurring defects in the instructions given to the agent.
The first defect occurs when a rule is written in ordinary prose rather than as an explicit, machine-actionable constraint. The second defect appears when instructions are framed negatively, telling the agent what not to do instead of defining the required behavior. The third defect arises when a rule lacks any verification step, allowing the agent to proceed without checking compliance.
The author notes that these patterns emerged consistently across tasks in programming, DevOps, analytics, and information security. By systematically rewriting instructions to eliminate prose form, negative phrasing, and missing checks, the frequency of apparent model failures dropped sharply. The conclusion is that "agent is dumb" is usually a diagnosis of the prompt, not the underlying model.

