Update: Thank you for taking community feedback seriously. This is now live!
I'll try to update this answer with usage experience. I've made this "Community Wiki". Everyone is welcome to edit in their experiences with it.
- http://stackoverflow.com/questions/24122169/server-error-in-application-existing-connecction-forcibly-closed-by-remote-h close voted with this reason. Looks like a great fit.
Yes, I definitely think this is a good idea.
- "Unclear" is ambiguous - The fact over 500 people have upvoted Can we please have the "Lacks Minimal Understanding" close reason back? clearly shows that a lot of people, me included do not use "Unclear" as a close reason for those questions as you've intended.
- The specific use case you describe is very common - having clearer guidelines on it can be very helpful. It can make the choice of closing or keeping open obvious.
- This close reason is clear - I think we have established that close reasons should be as clear as possible with all the discussion and abuse of "lacks minimal understanding". This is definitely a step in the right direction.
- It's polite - it does not imply anything about the author but rather focuses on the question which is huge in my opinion. We shouldn't criticize the author themselves, but the question.
- It's helpful - it points the OP to the resources comments would point them to otherwise, and it describes the steps to mitigate the problem precisely. "Unclear" is nothing like this.