The Metamorphosis has a dispassionate and realistic tone. Gregor's transformation is described matter-of-factly, or as if it could have happened to anyone. This neutral and dispassionate tone makes the transformation that much more horrifying while also contributing to the disconnect between Gregor and the other characters of the story (who react to Gregor with a horror not frequently present in the narration or Gregor's own thoughts).
Gregor's inability to communicate with others is more horrifying than the metamorphosis itself, and it creates a frustrating and futile tone. To speak and not be heard—and in fact to be actively reviled for speaking—is to live a life completely unconnected from what is human. The further disconnect between Gregor's mind and his body is equally frustrating, with seemingly simple movements often requiring conscious thought and planning.
There is also an anti-capitalist condemnation of a working person's life, both through Kafka's description of Gregor's job and also Kafka's description of Gregor's father's job. This anti-capitalist tone is furthered through the detailing of Gregor's family's financial situation, although it is ultimately revealed to be less dire than Gregor believes it is at the outset of the story. Ultimately, the short story is a critique of modernity's absurdity—in the philosophical sense of the term—but without a proposed solution, as is somewhat inherent to absurdism itself.