AmerginLiath
Adventurer
I don't have the DMG (I've looked through it at the bookstore, but couldn't afford yet to buy it), but it strikes me that that's not too far off from how that book suggests doing such options. As I recall, Disarm and Trip attempts are like Grapple or Shove attempts, where they're Attack Options that aren't proper attacks and involve contests of abilities/skills but don't actually – unlike the Battlemaster maneuver – take place during an attack and result in damage.