Loot Tables are not working correctly

Hey Guys,
I want to summon a mob with the following Death Loot table:

{"pools":[{"rolls":1,"entries":[{"type":"item","weight":1,"name":"minecraft:stone","functions":[{"function":"set_nbt","tag":"{Tags:[\"1\"]}"}]}]}]}

I want that it drops a stone Item which has a definite Tag.
This doesnt work.
Help is appreciated.