The principle nobody states out loud There is a one-line principle that quietly governs almost everything good about prompt engineering: Every ambiguity you leave in a prompt is computational work the model wastes guessing. This sounds abstract. It's not. It's the single most useful lens for understanding why one prompt produces work you'd ship and another prompt — for the same task, on the same model — produces something you'd be embarrassed to send. Once you see it, you can't unsee it. The two jobs the model is doing When you give an AI model a prompt, it's almost never doing one job. It's doing two: Figure out what you actually want. Produce it. Job 2 is the one we think about. It's the visible work — the writing, the code, the analysis, the summary. Job 1 is invisible. It happens inside the response. The model has to infer: What's the deliverable? A draft? A finished product? A list? An essay? Who is producing this? Me as a generic assistant? Me as a senior engineer? Me as a consultant? Who's it for?…