The agent reviews the code. The agent has access to tools. It writes the code, runs it through a test, reads the error, fixes the code, keeps going. It passes the code off to another agent with a prompt to review code and give it notes. They pass it back and forth, another agent reads and creates documentation. It keeps going and passes things back.

Now that's the idea anyway. Of course they all will lie to each other and there's hallucinations every step of the way. If you want to see a great example look at the documentation for the TEMU marketplace API. The whole API system, docs, examples etc appears to be vibe coded and lots of nonsensical formatting, methods that don't work and parameters in example that just say "test" or "parameters", but they are presented as working examples with actual response examples (like a normal API) but it largely appears to just be made up!