This chapter examines methodologies that allow intelligent agents to systematically assess their performance, monitor progress toward goals, and detect operational anomalies. While Chap. 11 outlines goal setting and monitoring, and Chap. 17 addresses Reasoning mechanisms, this chapter focuses on the continuous, often external, measurement of an agent’s effectiveness, efficiency, and compliance with requirements. This includes defining metrics, establishing feedback loops, and implementing reporting systems to ensure agent performance aligns with expectations in operational environments (see Fig. 19.1).