2012 prius rear brakes.

Hopefully not an anti-seize molybdenum paste? That stuff is good for shim to pad to caliper contact, but definitely not good for pins. Again, Sil-Glyde Brake Lubricant is one readily commercially available pin lube, can be used on rubber boots, and bleed bolt caps too. You probably recall: the stuff on there from the factory has that pasty silicone gel appearance. Toyota sells something too, has a pink tint? But Sil-Glyde is tried-and-true.

 

The last time I bought a factory caliper from Toyota and took it apart, the stuff in there was, recognizably by sight and smell, the pink lithium-soap-based glycol grease that they sell under the name "rubber grease" and refer to in the manual.

I've never tried Sil-Glyde so I won't say it doesn't work great. (I still have a tube of Ford's old silicone brake grease from years ago when I had a Ford, and I use it for all kinds of things, on cars and off.) But for the record, Toyota has not spec'd a silicone here.

-Chap