That sounds hard to do in a natural language. Maybe they could deliver the unambiguous specification in a formal language designed specifically for the purpose of specifying what programs are supposed to do.
If I could get unambiguous specifications, then my job might actually be in trouble. It would cut my workload down considerably.
I was half joking, because software development is largely the process of developing an unambiguous specification - just in the form of executable code.
A premium on the ability to express requirements clearly and logically, on the fly rather than as part of a cycle of paper-pushing.