To identify the number of interactions handled by an agent per day, we should look at reports specifically designed to track agent performance metrics. The Agent Metrics Export Report provides detailed metrics about agent performance, including the number of interactions handled per day. Similarly, the Agent Metrics Report is explicitly designed to display various metrics related to agent performance, such as the number of interactions handled per day. Other reports like Agent Login-Logout Details Report and Agent Quality Details Report focus on different sets of data, such as login times and quality scores.