When a risk manager notices that the risk register is missing key data, the most critical information they will require first includes the risk description, risk probability, and risk impact. These elements are fundamental to understanding each risk and planning appropriate responses. The risk description provides a clear understanding of what the risk is, while the probability and impact help in assessing the severity and likelihood of the risk occurring, which are essential for prioritizing and managing risks effectively.
PMI's risk management guidelines emphasize the importance of having these core data points to effectively manage risks throughout the project lifecycle.