The 18-year-old signed a new deal at Melwood on Monday afternoon having impressed during five first-team appearances.
Director of Football Comolli told Liverpoolfc.tv: "He did very well when he played for the first team last year, especially against Arsenal (in April). Then he's done well again this year and he's done well for England, so it's fully deserved.
"He's bright, which is very important to succeed at the top level. He's dedicated, he's committed, he's very professional. He's one of those who is very positive and he listens to what other people have got to say, whether it's the manager or coaches or the fitness team.
"I've just told him: it's a contract but you can't rest on your laurels. He's still got a long way to go, he's still got a lot of work to do physically, mentally, tactically and technically - all aspects he can improve.
"He knows this, but all the elements are there to make him a very, very good player."
While Robinson faces a tough test to oust Jose Enrique from the left-back slot, Comolli has also revealed that the youngster will soon face even more competition.
He explained: "We've got one or two more good left-backs (at the Academy) who are probably as good as Jack was at their age. There will be competition for Jack in a few years.
"The most important thing is that there's talent coming through. Hopefully the future of the club is bright on that side."