If you want to understand why an AI agent works, learn this one diagram.
It will save you time.
Something comes in. Text, an API call, a webhook.
The model looks at it. If it can answer, it answers.
If it can't, it breaks the job into steps, calls a tool, and reads what came back.
Then it checks whether the goal is actually done.
That's the loop.
Memory is two things, not one. The current run. And what should still be there next week.
Guardrails sit on the path. Permissions, approval gates, rate limits, a human checkpoint. Not a box you add at the end.
Observability sits underneath. Traces, cost, latency. Without it you're guessing why it failed.
ChatGPT, Claude, Gemini, a thing you built last quarter.
Same skeleton.
Different tools in the action layer.
One page.
Enough to see where an agent actually lives, before you start building.
What would you add?