Fundamentals·6 min read
What Is an AI Agent, Really?
A practical definition that goes beyond the hype — and what separates an agent from a chatbot or a workflow.
What Is an AI Agent, Really?
An AI agent is a system that uses a language model as its reasoning engine to decide what to do next in pursuit of a goal — not just to respond to a single prompt.
Agent vs. Chatbot vs. Workflow
- Chatbot: replies to a message. No memory of yesterday. No tools.
- Workflow: a fixed pipeline. Always runs the same steps.
- Agent: given a goal, chooses tools, recovers from failure, and remembers what matters.
The four pieces
- Reasoning loop — the model decides the next action.
- Tools — what the agent can actually do (search, write, call APIs).
- Memory — what it remembers between turns and between sessions.
- Guardrails — what it must not do.
If a system is missing any of these four, it's probably closer to a workflow than an agent.