You’re right that it’s a fuzzy line. That said, if you can make the contract/handoff between agents deterministic, you’ll always get better results by doing that, compared to letting the agents try to handle it through inference, since there will always be some error rate.

For this reason, I think that for at least the next couple years, even very advanced agent systems are likely to have a lot of deterministic control flow and glue in their guts. To me, that doesn’t make them “not multi-agent”. Rather, this is how you can build multi-agent systems that actually work in reality. But much of it comes down to semantics, admittedly.