Having used MTR on my mac and on Linux system I was always frustrated with the lack of this option from the Junos CLI. You have always been able to start a shell and run MTR as below:-
nick@ScoobyDoo> start shell
% mtr 126.96.36.199
Although it’s super handy, the inconvenience of starting the shell can be a PITA.
I thought i would have to live with this until I found the following:-
nick@ScoobyDoo> traceroute monitor 188.8.131.52