I've recently picked up Storm King's Thunder after my homebrew game came to a halt. Main reason for this is that I bought Volo's Guide to Monsters, Xanathar's Guide to Everything and Mordenkainen's Tome of Foes.
My players really want to try out the new classes and races, but I've ran out of ideas to continue in the homebrew game, so I picked up a published adventure. On the back I noticed that the book should be used with the PHB, DMG and MM. I imagine this refers to requirements for GM'ing, but it made me wonder if there were any other restrictions.
So far I could only find that it's recommended to have at least one character with the ability to understand Giant in the "How to run the game" section in the book when you run Storm King's Thunder.
Are there any restrictions or other things I should keep in mind when I allow my players to play classes and races from other official source books in published adventures? (e.g. certain race traits that affect parts of the story or powerful new classes)