We'll do a good number of explications during the semester. In my experience, students must write several of them before they get the hang of the assignment. During this learning period, it helps to have a longer description of the assignment for reference. An explication is a miracle of conciseness made possible by intense clarity, not a simplification made possible by omission. Arguments in their natural habitat are not nearly as crystalline as the arguments in a logic textbook.
Explications summarize without judging.
If the original argument is weak, an explication won't patch it up but expose it. If the original is strong but draws on premises scattered over a large area, some of which are vaguely stated or even unstated, and mixed together with arguments for other conclusions and irrelevant matter, then the explication drops the claims irrelevant to that argument, no matter how important they may be to other arguments made by the author, gathers all the relevant premises together, no matter how obscure and scattered they may be, makes them explicit, restates them with new clarity, puts them in logical order, and presents the argument in crystalline purity. The point of explicating arguments, of course, is that arguments are much easier to understand and assess when laid out in this way than when they lie camouflaged in their natural habitat. This is another way of saying that you need not agree with an argument to explicate it well. In fact, you should always explicate an argument before you decide whether you ought to accept it, indeed, as part of the decision whether to accept it.