Define what a correct output is
Sampling only works if reviewers apply consistent criteria. Anthropic's guide to defining success criteria recommends criteria that are specific and measurable, and reminds teams to consider edge cases. For a document extraction workflow, that might mean each required field matches the source document exactly. For a drafting workflow, it might mean the draft contains no statement unsupported by the provided sources.
Write the criteria down and give reviewers examples of pass, fail and borderline cases. Record reviewer decisions in a structured form, not in free-text comments, so they can be counted.