Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Serious, Honest, Keeping it Real, Intellectual, Philosophical, Deep Thoughts
One way to think about War and Peace is as a novel that's trying as hard as possible to tell you the truth. The truth about relationships, the truth about home life, the truth about the way boys and girls grow up and mature – as well as the truth about politics, army life, and how war actually happens. There's always this urgent earnestness in Tolstoy's tone. Not that he totally lacks humor, but overall he tends to just calmly point out where others have gone wrong, and how a reasonable person would see the situation. Check out this section for some sense of how he rolls:
people accustomed to think that plans of campaign and battles are made by generals [...] forget, or do not know, the inevitable conditions which always limit the activities of any commander in chief. The activity of a commander in chief does not at all resemble the activity we imagine to ourselves when we sit at ease in our studies examining some campaign on the map, with a certain number of troops on this and that side in a certain known locality, and begin our plans from some given moment. A commander in chief is never dealing with the beginning of any event [but instead] is always in the midst of a series of shifting events and so he never can at any moment consider the whole import of an event that is occurring. Moment by moment the event is imperceptibly shaping itself, and at every moment of this continuous, uninterrupted shaping of events the commander in chief is in the midst of a most complex play of intrigues, worries, contingencies, authorities, projects, counsels, threats, and deceptions and is continually obliged to reply to innumerable questions addressed to him, which constantly conflict with one another. (22.214.171.124)
Even though he's pointing out a glaring error that most of his readers have been making all their lives, Tolstoy doesn't call anyone out on the mat for it. Instead, we get the sense that he knows it's not our fault that we don't get how military campaigns work. "People forget, or do not know," rather than just straight-out ignore obvious facts.
Even more than that, the narrator puts himself in the shoes as the reader, showing how he totally gets how much readers want to believe that everything happens in an orderly, directed fashion. Notice how he slips into the first-person plural "we" to talk about what we "imagine to ourselves." Only after that nice pat on the back do we get the actual correction: that events are a bunch of connected moments that don't stop or pause like a video game but just keep on going and have to be responded to in real time. The argument builds and builds till the logic is too overwhelming to question – how could anyone dismiss that long list of the kinds of things that a commander has to keep constantly juggling, from "intrigues" to "projects" to "deceptions"?