A vague requirement creates precise disappointment.

A vague brief does not lead to vague results. Somebody has to build something specific, so they fill your gaps with their assumptions, and you eventually receive a concrete thing that is precisely not what you had in mind. The disappointment is sharp even though the request never was, and it was created by the ambiguity you left.

When you ask for something, describe what done looks like, including one example of a version you would not want. It takes a few extra sentences. It replaces a later conversation where both of you are frustrated and neither of you is wrong.