The following will provide the answer as to how much descriptive narrative is required for a story to be clear to your readers. I warn you: the answer is frustrating. Be warned and read on:

Just as there are many different writers in the world, there are many different readers. Many. Different. Readers. Both content creators and content consumers follow patterns and methods to do what they do. Some of them will never cross paths. For instance, a regular reader of Jonathan Franzen isn't likely to be reading Jonathan Maberry. Once you get past the mechanics of writing, one of the thorny problems that follows is how much handholding to give your readers? A huge X factor is a reader's background. If they've had a privileged life, then the inner workings of street-level crime will remain out of reach in their imagination without extensive or explicit description. Conversely, someone who's spent some time observing or living a criminal lifestyle will only need a few cues to be good-to-go for the rest of the story.

My main concerns when crafting a tale can be broken down into two aspects: clarity and entertaining (in that order). Whether or not a reader has enjoyed my work becomes a moot point if they couldn't understand it. They'll never be entertained if they think a character is running and texting and picking their nose and reading a book at the same time (and not in a super-cool, magical, speculative fiction way). There is nothing more frustrating than putting a story together, submitting it, and getting a rejection with feedback (which is good) that specifically alludes to not understanding the action (which is bad).

Again: why am I writing about this? Well, duh, I just got a rejection notice that had a smattering of "I didn't understand what happened when..." in it. When I re-read the piece, I could see where some of it deserved more description, but I couldn't see, for instance, why a reader would think two completely different objects, described in two different places would become conflated. Taking some time with the feedback, however, I began to see where a disconnect in what it takes to trigger the imagining of a particular environment or situation can cause later actions to become unclear.

Comments are never as precise as they could or should be. Nor are they ever what you want to read. In fact, they're usually so downright infuriating because those comments seem to be missing the point entirely. How could these fools not understand my work!? What us content creators need to realize is that the comments are definitely a reaction to something in the story, but not necessarily what the comments themselves say they are reacting to. Huh? What I mean is that people often don't realize what they're reacting to, they're just reacting.

And now, to answer the question: how much description needs to be spoon fed to your readers? Not much, but just enough in the right places.

Frustrating, right?