The question as to whether any given text of scripture is prescriptive or descriptive can be ascertained by good biblical interpretive practices. Some important questions:
Has a pattern of behavior been established within a text or its context?
Is that pattern verifiable or based on assumption?
Beyond a pattern, has this behavior developed into a practice?
Has that practice been established or incorporated into church life?
Is the pattern or practice for all believers for all time or for a specific group of believers for a specific time?
Is that practice to be modeled by us and passed on to future generations of the church?
Is the practice, pattern, or model directly commanded or just inferred from the text?
Does the particular passage simply recount history or is it instructive for the future?
Does the passage describe what certain church actions looked like, or does it prescribe what they should look like?
This is not an exhaustive list of questions to ask before deciding whether a passage is prescriptive or descriptive, but sufficient to begin resolving the question before considering any text.
Also, in consideration of answering this question, we need to do a bit of self reflection.
Have we matured enough in Christ so as not to bring our preconceived notions into the text?
Do we have a tendency to want others to behave the way we do?
Are we judgmental of others who have a different way of expressing their faith because of our personal conclusions?
Are we more concerned with a model, mode, or modification that we have established by experience, or are we willing to consider that the Spirit may be leading us to accomplish His will in a way that might be peculiar to others?
Do we have an inclination to be controlling?
Do we tend towards already made conclusions, or are we willing to reexamine how we arrived at those conclusions.
All scripture is profitable, this is true, but just because something profits us in our lives, does not necessarily mean it dictates a course of action for our lives.