A useful feature for client side encryption would be to execute a RawBSONDocument as a command without decoding and without modification. This would increase performance and avoid BSON-Python-BSON round tripping errors, like changing uuid subtypes.

Note since this would be internal and only used for communication with mongocryptd the proposed database._raw_command method would not need to support sessions, read_preference, compression, or anything else besides OP_MSG.