May I suggest that you indicate the number of levels (or total elevator energy requirements) that a particular mission has.
Some missions are just a single level whilst others are spread over two/three levels. Later missions my be spread over four or more. Without some idea of how long missions are, I can't effectively plan my playing time or energy usage. Am I likely to be able to complete this mission before I have to go out/go to bed? Do I have enough energy for the elevators or am I going to get part way through and then have to make the choice of either abandoning the mission, obtaining Crystal Energy, or purchasing an elevator pass so I can finish it?
A small icon within the mission description, preferably near the start button, would suffice. e.g.: "20 (-)". Thanks.
While I'm not in disagreement with this, you can check from the Mission Lobby.
Since it counts as Depth 0, you don't get charged a fee for going to the Lobby. Once there, click the Gear Icon then click Gate Map. It'll tell you how long the mission is.
~Sev