Say you are given a mock-up of 25 screens of the visual states of your application. The expectation is that this is enough for us to be confident we can develop and hand it to the original stakeholder or customer as a finished application, and they will be satisfied. Naturally, you're going to end up asking the stakeholders many questions over again that were used to come up with the UI, which is wasteful.
However, I have many many times found that this is very much not enough, in the course of developing the application the requirements become blurred by the fact that we are replicating an interface and in the end the customer is not as happy as they first seemed when we asked them for all the info to create the UI.
I am just not sure what else to ask for, I have tried to be specific and ask for requirements and an understanding of the overall goal, but I don't know what I should ask for. If I just start now, lots of time is going to be wasted re-hashing all the info that lead up to the UI and during this phase many important reasons the customer originally had will be lost.
How can I get people to understand that we cannot lock down requirements based on UI mock-ups by asking for something actionable they can create for me?
What would you ideally start with in order to properly execute the task of developing an application for end users?