The effect of “Des Frog” is a Trigger Effect that can be chained to. It activates when “Des Frog” is Tribute Summoned successfully.
Count the number of “T.A.D.P.O.L.E.(s)” when you resolve this effect, not when it activates.
If you activate the effect of “Des Frog” but have no “Des Frogs” in your hand or Deck, your opponent can check to confirm.