Some of our cities were getting so many questions like that that a few years back we began working with some of them (the cities) and the property owners to put together a "property showcase" for them to market those higher profile properties. We invited together the planning and council members, local developers, brokers, and some bankers. We had our architects draw up sketches and renderings to show the developers what the cities wanted to see, ran fiscal and economic impact models to help the councils and planning commissions see possible spin-offs, etc. Over the years we've had a few deals come to fruition that were basically exactly what the cities wanted and were done by developers who we put in the room with the property owners and the cities in those showcases so we count those as successes. We've also had a few developments that probably happened as a result of the matchmaking that goes on in the showcase since a property owner may have another parcel or two that a developer had that wasn't on display at the showcase.
This seemed to work well for those properties that are too small for any sort of industrial use or something flashy that might get some incentives but helps the communities to market potential retail or commercial lots. We stopped doing it for a few years because of the pandemic but we've had enough interest from the local brokers and developers that we've brought it back for this year.
I dunno if this helps in dealing with your annoying agents but at least it gives the city a venue to be proactive about a vacant lot... of course, we've always got some cities in the county or some property owners that have absolutely no desire to participate, so...