I have two Mongo DBs. One for my dev environment, one for production as seen here from my Robomongo setup:
The production db is SSH tunneled to my Digital O
dstHost needs to be a hostname/IP, not a MongoDB connection string. In this particular case, you can actually omit dstHost, localHost, and localPort in this particular case because they already default to the values you're providing.
dstHost
localHost
localPort