Bring up the positive facts about the scoring and feedback collecting - HappySignals will make also the agents happier.
Make sure the Service Desk teams and managers understand why you are implementing HappySignals. Show them how HappySignals works from the end-user perspective and how they can see the scorings and feedbacks.
Never think or communicate to Service Desk Agents that they will be somehow ranked by the Happiness Score - they should not be. If you do that, you risk ending up in a situation where agents start to avoid handling complicated tickets.