When it comes to the artistic direction of the music I have had people give me absolutely no direction what so ever up front. It would probably make a good article (Questions you should ask the project lead to hone in on the right sound perhaps?) Sometimes the project lead has a good idea what it should sound like, but an atrocious ability to describe it to you.
This topic has come up often at conventions and lectures like GDC. I've always preferred to discuss everything but the music. Tell me the emotion(s) the player should feel. Describe or show me the world. What's the pace/mood of this level? What's the overall plot of the game and where does this level/spot of the game fit into it? Etc.
If you must discuss actual music, go this route:
If you could put any soundtrack in your game, what would it be and why? Ask for several references to help triangulate the musical goal.
And by all means - avoid musical terminology, even if the project lead thinks they know something about music. Because I've had it backfire before. Instead, discuss tangibles that orbit around the music so you, as the musical expert, can understand what kind of gap the music needs to fill. After all, discussing music can be highly subjective and some terms don't always mean the same thing. Case in point: I once had a Disney exec tell me to make a piece happy and peaceful like this reference piece:
Perhaps Adagio could be conveyed as peaceful but happy? No way! So in this case, thankfully I'd ask for no less than three references per theme and a paragraph describing the level and plot at that point in the game. I leaned on those other references and completely ignored Adagio for Strings, although I love the piece!