It's not that Tan doesn't give her writing over to the odd flights of fancy—"pigeons gurgle" (5), "wind murmurs" (39), and phantom nightmare moms come after our heroine with unstoppable chess-based minions (68). But by and large, Tan avoids flowery text in favor of delivering the facts. She allows the emotional tone of the story to creep in from the unspoken things; the things we associate with her descriptions color our understanding of the situation rather than the descriptions themselves. Think of it as a sideways approach to creating the emotional tone.
For example, take a gander at this passage from the end, where Waverly waits for punishment after running away:
Standing there waiting for my punishment, I heard my mother speak in a dry voice. "We not concerning this girl. This girl not have concerning for us." Nobody looked at me. Bone chopsticks clinked against the inside of bowls being emptied into hungry mouths. (65)
She doesn't say anything about how people feel or what they look like; the only word she uses to describe her mother is "dry," which is a pretty neutral term. But it also expresses a sense of distance and general lonesomeness, as do the "bone chopsticks" that make a repetitive clicking sound. Tan says a lot without seeming to say much at all. In this case, Waverly's loneliness is palpable.