Your Thesis Can Be A Blueprint
A thesis can be used as roadmap or blueprint for your paper:
In "Résumé," Dorothy Parker subverts the idea of what a résumé is--accomplishments and experiences--with an ironic tone, silly images of suicide, and witty rhymes to point out the banality of life for those who remain too disengaged from it.
Note that while this thesis refers to particular poetic devices, it does so in a way that gets beyond merely saying there are poetic devices in the poem and then merely describing them. It makes a claim as to how and why the poet uses tone, imagery and rhyme.
Readers would expect you to argue that Parker subverts the idea of the résumé to critique bored (and boring) people; they would expect your argument to do so by analyzing her use of tone, imagery and rhyme in that order.