The one-page designer brief
Give the designer exactly six inputs: the single message in one sentence; the audience in one sentence; the offer and response device verbatim; the unit and the title's spec sheet PDF, unedited; two or three ads from the actual magazine so the work is designed for its neighborhood; and the legal lines that must appear. Then let them design. Briefs fail by omission of the spec sheet and by inclusion of a mood board.