Documentation-Driven Development for AI Features

Write the Docs First

Before writing a single line of code for a new AI feature, I write: 1. The API documentation 2. Three example use cases 3. The error messages users will see

Why This Works for AI

AI features are uniquely hard to spec because behavior is probabilistic. Writing docs first forces you to answer:

• What does "success" look like? (Define quality metrics)
• What happens when the model fails? (Fallback behavior)
• What should users never see? (Safety guardrails)

A Real Example

For our summarization feature, the doc-first approach revealed: - We needed a confidence score (users wanted to know reliability) - Error messages had to explain why summarization failed, not just that it did - The API needed a max_length param we hadn't considered

All discovered before writing code. Weeks saved.