Why is tone so difficult in poetry?

Tone is both easy and difficult. It is easy because the
beginning and ending of an analysis of tone in poems is the formulation of attitudes
present in a poem, or a statement about the appropriateness of diction, imagery, or
metaphor to the content. Usually these judgments are readily described. It is also quite
difficult, however, because a full discussion requires not only the articulation of an
attitude but also the analysis of how the poem permits the reader to draw conclusions.
Thus, any investigation of tone is complex, requiring students to show the interaction
of poet, material, reader, situation, word choice, fairness, completeness of
development, truthfulness, and structure, together with anything else that might have a
bearing on the proper interpretation of attitudes. When you think about the way readers
describe the tone in a poem, readers may respond by saying “irony,” “humor,”
“disingenuousness,” “indignation,” “pathos,” or a number of other descriptive terms. It
is never a matter of simply memorizing words but a constant study of vocabulary so that
you already know the word in hand. The problem becomes explaining the means by which the
poem enables you to make these assessments.