When I first read Artificial Intelligence: A Modern Approach (3rd Edition) by Stuart Russell and Peter Norvig, which I will refer to as AIMA, the idea of an agent felt remarkably clean as a being that perceives an environment through sensors and affects it through actuators. That framing made everything fall into place because a percept became simply what the agent experiences, and a percept sequence became the accumulated record of its experience over time.
AIMA and the Discipline of Clear Definitions
What stayed with me most was not the classic robot or vacuum examples, but the discipline AIMA demands in separating concepts, since it treats the agent function as an abstract specification that maps what has been perceived to what should be done, while the agent program is the concrete implementation that runs on a particular architecture. Once I absorbed that separation, I became less interested in arguments about which tool or prompt is superior, because the real question is always what we want the agent to achieve, where it operates, and what information it can legitimately rely on.