How Detailed Should Requirements Be?

And who decides? And when?

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Recently I was chatting at a wine tasting with two lawyers I had just met. One was working on a case involving software. She asked me, “How do you know how detailed to make the requirements?” It’s an insightful question, one that even experienced business analysts often wrestle with.

There’s no single correct answer to this question, even assuming we could agree on exactly how to measure requirements “detail.” As with many such questions, the correct — but not very satisfactory — answer is: “It depends.”

Though I can’t give you a simple answer to this very important question, I can suggest some ways to think about how much detail is appropriate in a given situation. This article is adapted from my book More About Software Requirements.

Who Makes the Call?

The central question to consider when deciding how much information to include in your requirements is:

Who do you want to have making the decisions about requirements details and when?

If you’re willing to defer many of the refined decisions about product capabilities and characteristics to the developers, you can write less requirements documentation. This can also…