Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Unsure; Brave; Hopeful
Savvy is a lot about how life doesn't always turn out the way you hope it will. Mibs decides she knows what her savvy is because she wants to help her father, but by the middle of the book, she thinks she's made the worst mistake in the world by believing she already knew what her savvy was.
Since Mibs is our storyteller, this keeps the story interesting. She's unsure of herself and unsure of how she fits into the world, and that means there are plenty of questions that we—as readers—are eager to find answers for. So when Mibs says, "I couldn't understand any of it. Nothing about what was happening felt right. What had happened to my savvy?" (7.23), we feel just as concerned and confused as she does.
And the thing about all the uncertainty that crops up for Mibs is that by forging ahead anyway, our narrator and main characters winds up bringing a whole lot of bravery into the tonal mix too. Bravery is not the absence of fear after all, but the ability to act in spite of it, which Mibs definitely does. There are countless moments when she could have given up or turned back—like when she realizes she's been wrong about her savvy or that there's an Amber Alert out for her and her friends—but Mibs keeps her eyes on the prize instead.
Which brings us to the overall tone of this book: hopeful. The story starts out almost hopeless—Poppa is in a coma and doctors are unsure if he will make it—but Mibs uses her own hope that things will turn out for the best to start her journey, and leans on it to carry her through to the end. She says:
I thought about the way my savvy hadn't worked out in the way I'd hoped or how our journey to Salina had taken its own twists and turns. Then I remembered what Lill had said just before falling asleep in the motel the night before. You never can tell when a bad thing might make a good thing happen. (33.37)
This idea—that there can still be light at the end of the tunnel no matter how tough the going gets—is the overarching tone to the book. It keeps Mibs—and readers—optimistic until the end.