When using telekinesis to grapple, what is the CMD to escape? The spell doesn't specify the CMD, just the CMB.
Combat Maneuver: Alternatively, once per round, you can use telekinesis to perform a bull rush, disarm, grapple (including pin), or trip. Resolve these attempts as normal, except that they don’t provoke attacks of opportunity, you use your caster level in place of your Combat Maneuver Bonus, and you add your Intelligence modifier (if a wizard) or Charisma modifier (if a sorcerer) in place of your Strength or Dexterity modifier. No save is allowed against these attempts, but spell resistance applies normally. This version of the spell can last 1 round per caster level, but it ends if you cease concentration.
Should I assume it works the same as black tentacles?
The CMD of black tentacles, for the purposes of escaping the grapple, is equal to 10 + its CMB.