The project specification closely ties in with the legalities, expectations and politics. Without clear specifications, you become vulnerable to the type of nonsense that prevents you from developing the type of functionality that is directly relevant to solving the problems that the project looks to address. Spending some time at the beginning of the project to define a clear specification to be made available to everyone working on the project will save a lot more time from being wasted on associated politics relating to changing interpretations and even agendas of other people working on the project.

A clear specification document is a useful asset that can be used to keep the team focused, as well as being a point of reference to deflect any development requests known not to be part of the original agreement.