How do you write a content brief?

Keep it to a page or nobody reads it. Mine covers the target query and who's searching it, what the reader should be able to do after, a rough H2 outline, the questions it has to answer (pulled from people also ask and the top results), a word count range based on what ranks, internal links to include, and anything the client doesn't want said. Then two or three ranking examples with a line on what each one is missing. Writers say that's the most useful bit.