re: Do better tools exist to control crowds/rioters?

Criminal prosecution works, but our legal system polluted by demprogs is intentionally broken.

Dyed water from a water cannon

Yes. Announce and even hand out cards that certain areas are Fed property and no one is allowed to trespass. Announce that vehicles will be entering and leaving, so protestors need to stay off the road. All for their own safety. Announce that trespassing or blocking the street is interfering with a Federal Officer, and is a felony.

First protestor that crosses a line - have 10 agents with shields and 5 more with zip-ties go out, surround it, zip-tie-cuff it, and haul it off and charge it with a felony, and no bail.

Have another group of agents that can take over as they process the 1st. Just keep going. When they see a few getting hauled off, they'll stop. Or get hauled off as well. Fine.

No pushing back, throwing to the ground to turn the protestors into martyrs (to the left). Just pick 'em off, one at a time. One right after the other. No spectacle.

Simple. In Japan they make it illegal to protest without a court permit so the have to name the principle organizers. Then if it gets out of control the principals go to jail. And officials spray blue dye that can't be washed off and arrest everyone who was sprayed. A few get away but notice that there are never protests in Japan.