The Kuo Toa entry for the MM spends at least half its considerable word count dealing with the various % of a creature carrying a certain weapon, the chance of various combinations of leveled Kuo toa and the ratios they come in. All of which is likely to be ignored by any DM of any ability. If you were new it is actively detrimental.
Add to the that the fact that the writing is rambling and verbose. Mechanical effects like how an attack works are hidden in walls of text. It’s riddled with spelling mistakes. The stat block is arcane and large parts are irrelevent.
I have great fondness and nostalgia for the MM2 book and its compendiums. But to say it’s the best of bestiary is gobsmacking. I’ve included the Kuo Toa entry so people can see I’m not exaggerating.