A complete task specification goes beyond describing what needs to be done. It should encompass the entire development lifecycle for that specific task. Think of it as creating a mini project plan that an intelligent but literal agent can follow from start to finish.
A discrete task description to be treated like a project in the GTD sense (anything above 2 steps is a project). At what point is this overkill, as in templating this project description may well lead to having the solutions once you've done this.