The Agent Model in AI Research

The intelligent agent model frames AI systems as entities that exist in an environment, perceive that environment through inputs—sensor data, text, database contents, API responses—and act on it through outputs such as commands, text, or function calls. An agent is considered rational if it selects actions that maximize its expected progress toward a goal given what it has perceived and what it knows. This framing covers a wide range of systems: simple programs that respond to current input according to fixed rules, and complex planning systems that maintain internal world models and reason over multi-step action sequences. Modern AI agents built on language models fit within this framework, using the model's reasoning capabilities as the decision-making core.

Types of Intelligent Agents

AI researchers distinguish several agent types based on how they reason and act. Simple reflex agents respond to current input alone using condition-action rules: if this input, then that action. Model-based reflex agents maintain an internal state to handle situations where current input is insufficient to determine what to do. Goal-based agents explicitly represent desired outcomes and select actions that lead toward those outcomes. Utility-based agents evaluate tradeoffs among possible outcomes using a value function, selecting actions that maximize expected utility rather than just achieving a binary goal. Learning agents update their behavior over time based on feedback from past actions. A contemporary AI agent built on a language model often combines elements of multiple types: it can reason about goals, maintain context across steps, and be improved through fine-tuning or in-context feedback.