What is the tone of the story "Gimpel The Fool"?

Isaac Bashevis Singer's short story, "Gimpel the Fool" is
written in an honest, literal, simplistic tone, devoid of sarcasm from the narrator.
 Instead, the irony is situational: Gimpel is a fool only because people think it so,
and he good-naturedly believes it too, only because it doesn't matter what people think
of him.

The story is a parable, a kind of morality tale.
 In this way, we have a reliable narrator.  The story, however, is humorous, because
Gimpel is just as he says he is:

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I am Gimpel the fool.  I don’t think myself a
fool.  On the contrary.  But that’s what folks call
me...

And yet, he's not.
 What Gimpel is in public, he is not in private.  When it comes to spirituality and
matters of the heart, Gimpel is no fool.  Rather, he is a believer, an optimist, a man
of his word.  He knows his wife is cheating on him, and yet he still loves her.  He
says:

What’s
the good of not believing? Today it’s your wife you don’t believe; tomorrow it’s God you
won’t take stock in.

Singer's
tone suggests that the reader and the townspeople should reconsider their definitions of
"fool," for a fool in this life may be in heaven in the next.