Prompt engineering

Prompt engineering covers how you phrase instructions, structure context, provide examples, and constrain output so a model behaves the way you need. Small changes in wording or structure can meaningfully change results.

In production it’s inseparable from evals: you can only tell whether a prompt change helped if you can measure output quality. Prompt changes shipped without evals are blind deploys.

Modern models follow instructions closely, so over-aggressive phrasing (“CRITICAL: you MUST…”) can backfire by overtriggering behaviors — another reason to validate changes against a test set.