What Makes an Agent Different from Autocomplete?
A prompted assistant answers one question and stops. An agent keeps going: it reads files, runs commands, looks at the results, and decides what to do next, on its own, in a loop, until the task is done.
The agent loop
Most agentic coding tools (Claude Code, Cursor's agent mode, Copilot Workspace) run something like this:
1. Read the task and relevant files.
2. Decide on an action (edit a file, run a command, search the codebase).
3. Take that action using a tool.
4. Observe the result (did the test pass? did the command error?).
5. Repeat, until the task looks done or it needs your input.
That "observe and repeat" step is the key difference. A one-shot prompt can't notice that the test it just wrote is failing and go fix it. An agent can.
Tools are what make this possible
An agent isn't smarter than a chat model, it just has tools: functions it can call to read a file, write a file, run a shell command, or search the web. Every action you've seen an assistant take, editing three files, running your test suite, fixing a failure it just caused, is a tool call, not magic.
| Chat / prompted generation | Agentic loop | |
|---|---|---|
| Steps | One request, one response | Many steps, chosen by the agent |
| Sees results? | No, it just produces text | Yes, reads output and reacts |
| Can fix its own mistakes? | Only if you point them out | Often, before you even see them |
| Your role | Write the prompt, read the answer | Set the goal, review the plan, approve risky steps |
Why this changes how you work
Because an agent can take many actions unsupervised, your job shifts earlier in the process: from reviewing a finished answer, to scoping the task well and putting guardrails on what it's allowed to do, before it starts. The rest of this course is about that shift.
NOTE
None of this makes the agent less accountable to you. It just means the checkpoints move: instead of only reviewing the output, you'll also review the plan, the tools it's allowed to use, and the diff, at different points along the way.