Most briefs describe a deliverable. The useful one describes a problem.
A brief that opens with "we need a new website" has already skipped the interesting part. A website is an answer. We want the question.
So the first call is not about pages or sections. It is about who you are losing to, what they have that you do not, and what someone believes about you before they ever hear you speak.
That conversation usually rewrites the brief. Sometimes it turns a site project into a brand project. Once or twice it has turned a brand project into a two-page note and no invoice.
Get the question right and the deliverable almost designs itself.