BlightCrawler
First Post
The rule of thumb is about saying yes- the question with disarm isn't, "Can you disarm?", the question would then be, "How do you disarm?". The rule of thumb doesn't apply to adding in mechanics, but dealing with the rules that are already there. If someone asks if something stacks, for example, the answer is yes unless the rules say otherwise.
That's definitely an important point. "Saying Yes" does not mean literally say yes, it's about giving people the benefit of the doubt and not shutting down an idea that's unexpected.
Although you can answer yes even to that, using DM's Friend. You can say, sure, do a melee basic (or Acrobatics check, or whatever seems to fit the situation) and the target will have a -2 until the end of his next turn as he fumbles to regain his weapon. And then if the player says "I'm going to disarm again!" You can tell them that it's not very creative, so they'll have a -2 to do it again.
However, even in these cases, when a player asks "Can I?" a better part of the "Say Yes" philosophy is to ask "How are you going to do that?" if the answer is not obvious. That will handle disarm, leaping from a balcony or trying to melt someone's brain with your mind (in other words, it forces the players to get creative if they really want to do it). If they can make it entertaining and creative, and fit the group's vision of the game, then keep on saying yes! It's all about fun (what fun means is up to you and your group).