What drives a project? What keeps you and your project team working together on the same page, focused on the same end goals and moving forward on the right tasks toward project completion? It's called communication.
If you're an agency, it's what ensures that everyone on the team understands towards which design or marketing campaign the team and client are working, the needs of the client, and how this campaign will be rolled out to your client and to the public. In short, communication is Job #1 for the creative director and project manager. It's the basis for accurately portraying what will happen on the project, and for ensuring that all client requirements are captured appropriately, in great enough detail that you and your team can move forward on a solution for your client.