I'm not sure if this is a bug, something that's not possible to do with the mod, or an issue with my script (I'm not super familiar with zenscript beyond recipe changing etc.) Here is my script:

Dropt.list("grassdrop")

  .add(Dropt.rule()
      .matchBlocks(["minecraft:tallgrass:*"])
	  .matchHarvester(Dropt.harvester()
		  .type("PLAYER")
          .mainHand([<primal:flint_workblade>.anyDamage()])
      )
       .addDrop(Dropt.drop()
            .selector(Dropt.weight(50))
        )
      .addDrop(Dropt.drop()
          .selector(Dropt.weight(50))
          .items([<charcoal_pit:straw>])
      )
  );

Any help would be greatly appreciated.

I'm not sure why .anyDamage() doesn't work. I'll have to look into it.

Instead of <primal:flint_workblade>.anyDamage(), try using <primal:flint_workblade:*>.

Also, I have a discord server for script help and stuff if you're interested in that: discord.codetaylor.com

I did end up trying <primal:flint_workblade:*>, which worked. Could it be a quirk of the specific modded tool?

I joined the server, thank you!