A great brief is short. It says who this is for, what it needs to make them feel, where it will run, what must not change, and when it is due.
References help, but explain why you chose them. 'This one, for the colour, not the composition' saves an entire round of revisions.
Tell us the constraint you are embarrassed about — the budget, the location you cannot change, the CEO who will not be filmed. Constraints are creative fuel when they arrive early and a crisis when they arrive on set.
Then step back. You hired a crew for their judgement; give it room to work.