Slot says Hughes' work was key in securing Mohamed Salah and Virgil van Dijk to new contracts.
"First, by bringing these contracts over the line, Richard deserves credit for that, and lots of credit," Slot said. "Because people have spoken for eight or nine months that so many things were not done right by us.
"In the end, we got what we wanted and Mo had, in most situations, when you simply look at his numbers, his best season so far in his history at Liverpool.
"And for Virgil it's difficult to judge this on numbers, but I think he's having a great, great season as well.
"Apart from him extending these two contracts, what I like so much about him is that I can do my job and he always supports me in the best possible way.
"Mostly people judge the sports director on the signings he brings in, I also like to judge him on how he lets me work over here, and giving me the confidence and always being positive, and creating a way of working which is ideal for every manager.
"So I would like to give him more compliments for that, than for the extending of the contracts, which I really like as well that he did that."