As Mallus said, you'd then have to decide whether to feed those descriptors into a task resolution system or a conflict resolution system, or something that mixes elements of both (Burning Wheel and 4e both involve mixing, each in a somewhat different way).
When attampting to be concise, I think the only choice is to feed them into the task resolution system. or, rather, if it isn't an integral part of the task resolution system, it probably shouldn't exist at all. And more to the point, if it isn't a function of the game's purpose, then it shouldn't exist at all.
"Big book" rpgs tend to go for a "kitchen sink" approach to rules and actions and potential activities. This is why they are "big books" (well, that and the need for designers to novelize the rules). More and more, though, indie rpgs take the genre back toward other kinds of games, where rather than being games about "anything goes" they are about a particular type of story or play experience. You wouldn't expect to be able to "do anything" when you sit down to play monopoly, so why would you expect to be able to do anything when you sit down to play an RPG? or, at least, that seems to be the thinking.
And I think there's some virtue to that indset sometimes. Certainly, having an "open world" game like Oblivion is great, but sometimes you just want to play God of War and rip through the levels, you know?
I think the only way to create an RPG in 10K words is to narrow the focus. So, can a "save the princess, slay the dragon/sorcerer/demon" rpg that is complete and fun be designed in under 10K words, and still be unquestionably an RPG?
I think so.