The assessment criteria used in the UPSC interview include evaluating communication skills, general knowledge, and the ability to articulate ideas coherently. Candidates are scrutinized for their understanding of societal issues, ethical considerations, and motivations for joining civil services. The panel also observes behavioral attributes such as empathy, leadership, and decision-making abilities under pressure. Ultimately, the interview aims to gauge a candidate's potential to become an efficient civil servant, capable of meeting the demands of public administration effectively.