The first person point of view in “The Tell-tale Heart” is very important because it contributes to the suspense. We are aware that the narrator is mad even though he tries to convince us he is not.
The narrator goes out of his way to tell us how clever he is. He knows he seems crazy, but he points out that he had to act and kill the old man because of his evil eye.
The disease had sharpened my senses—not destroyed—not dulled them. Above all was the sense of hearing acute. I heard all things in the heaven and in the earth. I heard many things in hell. (p. 4)
The first person point of view allows us to be inside the head of the narrator, and we can feel the suspense deepen as he continues his descent into madness.