The tone of a short story is established from the very beginning.
A short story’s tone is the author’s attitude toward the subject. Although the tone may change, it is less likely to change in a short story because of the shorter nature of the text. It is not true that the tone is not established until the end, because every paragraph and phrase establishes the tone.
Consider, for example, the opening lines of Edgar Allan Poe’s classic story “The Tell-Tale Heart.”
True! —nervous —very, very dreadfully nervous I had been and am; but why will you say that I am mad? 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. How, then, am I mad? Hearken! and observe how healthily —how calmly I can tell you the whole story.
This paragraph sets the tone for the entire story. We are in for a lot of this kind of language. The story describes the ravings of a madman. He is going to explain why he killed his roommate, all the while trying to convince us that he is not crazy. The tone is frenzied, desperate, and incoherent.
Another example is Shirley Jackson’s “The Lottery.” Although we are only granted small details of what is happening as the story moves along, the writer is very careful to establish from the beginning a no-nonsense tone as she describes a day in the life of the village.
The morning of June 27th was clear and sunny, with the fresh warmth of a full-summer day; the flowers were blossoming profusely and the grass was richly green. The people of the village began to gather in the square, between the post office and the bank, around ten o'clock; in some towns there were so many people that the lottery took two days and had to be started on June 26th.
The calm, matter-of-fact tone actually continues throughout the story, even as people are being stoned to death. Only through the protests and begging of the victim do we get any indication that something is wrong. Otherwise, it could be any village gathering anywhere in the world.