So many phrases come to mind when thinking of the tone of The Color of Magic: funny, hilarious, cheeky, sly, just-wicked-enough, good-natured, and whimsical—to name a few. It's the tone of every good comedian and satirist, and it's present on every page from title page to those advertisements nobody reads in the back. Here, take a look:
The enormity of this lie was so great that its ripples did in fact spread out one of the lower astral planes as far as the Magical Quarter across the river, where it picked up tremendous velocity from the huge standing wave of power that always hovered there and bounced wildly across the Circle Sea. A harmonic got as far as Hrun himself, currently fighting a couple of gnolls on a crumbling ledge high in the Caderack Mountains, and caused him a moment's unexplained discomfort. (1.8.53)
This passage escapes an uptight style in several ways. First, it uses engaging verbs with fun adverbs such as "bounced wildly." It also keeps a conversational tone with little additions like "in fact," which in a more formal style would be edited out for being unnecessary. Finally, this passage is completely unnecessary. True, Hrun will appear in the second and third stories of the novel, but here, there is absolutely no point in his being mentioned as alive, fighting gnolls, and becoming subconsciously aware of the life. Well, except for that it's funny.
Humor is ultimately what dictates the tone of this novel. Funny? Keep it. Not funny? Forget about it.