Learn English – Proper response to “Do the needful”, when the “needful” might not be clearly defined

I have worked in various places where "do the needful" is quite the common idiom. However, in some situations, both parties might not be quite aligned precisely with what falls under the scope of "needful".

Is there a concise idiom that one can respond with to clearly convey that, while it may be blatantly obvious to the requester what classifies as "needful", it is not so clearly defined to the party who the request is directed towards?

Edit:

For those of you unfamiliar with the idiom, it is an Indian English phrase which loosely translates into something along the lines of, "I assume that it is clear to you what needs to be done as well as how to do it, so kindly do so." Essentially, what I am looking for is a proper response that is along the lines of, "Sorry, but your assumption(that either I know what needs to be done or how to perform it) is invalid."

Edit:

This question is simply out intellectual curiosity as to whether or not a concise, idiomatic response exists.