I guess I feel like if you're in a situation where:
a) The player says "I smash the vase"
b) The vase has a trap of some kind
c) None of the PCs has investigated the vase or whatever it's sitting on for a trap
d) There's nothing in the area that the character would have noticed that the player simply isn't yet aware of
e) You don't trust the player to roleplay appropriately if you ask for a clarification
Then I'd just assume the character would act without any forethought. To me that would probably mean picking up the vase and throwing it against the ground, wall, or some hard surface.
Ideally I would just say, "Alright, you pick it up and smash it against the floor." Then I'd wait for the player to say something. This is their last opportunity to alter their fate. If they say, "No, wait, I don't want to touch it. I want to hit it with a sling bullet from across the room," then that's what happens.
If instead they say, "What's inside?" or "What happens?" then they're implicitly okay with their PC picking up the vase and smashing it against the floor. At that point I think it's pretty hard to argue that both the player and the character were acting a little carelessly, and that's exactly what a trap is designed to catch. If the player was going to search for traps, they've had more than enough opportunity to do so. If they wanted to search for traps, they should already have stated they intend to do so.
Even if it's magical touch paralysis trap, this works because you can just rewind time a bit if they fail their saving throw. It doesn't matter because they've already committed to the action.
I don't think I would run it in that ideal manner all the time. I think I would tip my hand at least some of the time. But I don't think that's a solvable problem in this situation. It's equally as much a problem that you've got a player that might be metagaming in a way you don't really like. But even that isn't necessarily going to be a problem at every table. Some tables don't care if players do that if it's honestly in-line with their characters. Others might be adamant that traps must be a secret to the player as well as the character.