Eval-Driven Development

What Is Eval-Driven Development?

AI features are nondeterministic, so "it looked fine in the demo" is not a quality signal. Eval-driven development maintains a curated test set with scored expectations and runs it on every prompt, model, or retrieval change, blocking regressions before they ship. It borrows the discipline of test-driven development and applies it to LLM behavior using metrics like accuracy, faithfulness, and LLM-as-a-judge scores. It is a defining trait of mature AI-First teams.