If you have a wire wheel you can put up in place of a grinding wheel on a bench grinder,,or hook up a wire wheel on an arbor and chuck it up in a portable drill and hold the drill in a bench vise, you can clean up rusted metal tools and parts very easily.
A light coating of oil,,most any will do inclu motor oil on the rusty parts and let them set for 5 to 10 min. You don't need very much.
Then wire wheel them with the oil still on them. They will come out very clean of rust and dirt. Any bare metal will be a smooth grey color. It won't remove plating from tools unless the plating is poor quality to begin with.
Wipe them down with a clean cloth or paper toweling.
I use the method in cleaning dirty and rusted gun parts and have for years.
Garden shovels, spades and small tools stay nice and clean, easy to work with if they are stuck into a bucket a few times that has just sand with some linseed oil mixed in it.
Motor oil will work as well but then you transfer the petro oil back to the garden and plants next time you work in the garden. It may be a small amt, but I don't care to have it in there anyway.