Descriptive case studies aim to describe in detail the phenomenon being studied. But can an interpretive paradigm be included to help with such description or is this going deeper than description and should not be included?
In my opinion, I think a descriptive study is interpretive in nature as when we describe a phenomenon, we can hardly avoid the interference of our own biased interpretation; that is, we can hardly avoid being subjective in our decision of what we choose to describe as well as how we are going to describe it. So I think the interpretive paradigm underlies descriptive studies more or less.
I also think that we can reap the benefits of this paradigm by having those participating in the event describe the happenings from their perspectives and comparing them with the researcher's. Or just like in ethnography, we can have participants share their descriptions based on their interpretation of their lived experience.
When you say 'can it include' an interpretive paradigm I imagine you are asking about how explicitly such a paradigm should be in any written report of your work. My personal view is that it is obvious that you will have an interpretive paradigm of some sort as you will bring this to the work. That already dictates some sort of account of where you are coming from when you interpret your data and the reader needs to know something about that. Similarly if you are saying that you adopt a specific (for example 'interpretivist' or 'constructivist' or whatever framework and if so which version you use. On the other hand scholarly journals and many readers get impatient with too much huffing and puffing in these areas and so I tend to keep that sort of thing as brief as possible.
Inclusion of interpretive paradigm in a descriptive case study will add value to the case. Whatever description we do in the case if it is supported and supplemented with interpretive paradigm it will enrich the value and relevance of the case provided it is brief, relevant and to the point.