Key features to look for in an AI tool for performance reviews include real-time feedback capabilities, customizable evaluation criteria, data analytics for trends analysis, goal tracking and alignment, 360-degree feedback integration, employee self-assessment tools, and performance prediction algorithms for actionable insights. Additionally, features like natural language processing for sentiment analysis, performance benchmarking against industry standards, and integration with HR systems for seamless data management can further enhance the effectiveness of the AI tool in streamlining performance review processes.