The key part of defining the task is establishing the success criteria – by which we shall know whether we are achieving the objective or at least making progress in its general direction.
Success has to do with values, ultimately with the values of the organization or the individual concerned. Performance has to be judged in relation to those values, which are usually implicit in the organizations purpose.
Evaluating or review process is not something that you, as a leader, leave to the ‘do’ at the end. Whenever you comment on progress – or the lack of it – or invite the team to consider their own agreed success criteria, you are performing the function of evaluating.