This is a big enough problem that there's not just one startup idea here, but several. For example, there will probably be one variant meant to filter out agents, but another meant to welcome them in an orderly way. This also seems an idea you could build more on.
Paul Graham: Agent Governance Holds Multiple Startup Ideas
Paul Graham says the agent problem is big enough for several startups: one product could filter agents out, while another could welcome them in an orderly way.