Many authors seem to believe that the agent's single responsibility is to sell a story to the editor. It is the agent who does the business side of things. While this is certainly one element, one of the biggest roles the agent plays is working with the author to make the stories truly great. Now, I guess I should say that there are agents out there who do not do this type of work, but many do.
But here comes the great twist to this. It is not just the agent who does the developmental editing side of things. It really is a teamwork. It is the goal of BOTH the agent AND the author, to make that story truly the best it can me.
I am in the middle of developmental editing with three of my authors right now. In each case, after I have looked at their stories, I provide directions I think the story should go. This is not the final decision though. What they all know is that this is just the ideas I came up with when working through the story. The authors all have their own perspective. The idea is that we find the best direction.
In some of the cases, we are just problems solving a situation in the story. Many times, in the writing process, the author is faced with a predicament, and is unclear which way to go. It might be something ranging from a point of view shift to a full plot shift. At this point, together we talk through where we think the story needs to be a couple of chapters down the road, or what we need the characters to be doing, or how this fits with the theme or the character development. Again, still working to make that story great.
The thing is that, if yo believe we are just essentially a sales person/contract lawyer, you are missing the mark. We are your team member.