No such things yet. Just marketing hype for a product people are creating.

It's currently a blanket term for gluing together a series of interactions via code and relying on LLMs for interpreting input or creating output data.

LLMs, no matter how clever can go off right now an execute an API request (e.g. execute something in a bash terminal like `curl -XPOST --data 'blah' <https://api-endpoint>`).