Definition of "one-note"
one-note
adjective
not comparable
(idiomatic) Having only one opinion, outlook, tone, etc., especially as expressed repetitively; without variety or range.
Quotations
The footnotes that attend Ambrose Bierce in the U.S. literary canon roughly place him as a minor writer of grotesque supernatural tales and trenchant war stories, a misanthrope, curmudgeon, a purveyor of stringing sarcasms, a one-note wit.
1992, Jane Creighton, “Bierce, Fuentes, and the Critique of Reading”, in South Central Review, volume 9, number 2, page 66
To his mind, there was only one right and true position on the question. This sort of one-note response is precisely the problem facing politically engaged academics in the U.S. at the moment.
2005, Anahid Kassabian, “Academic Frostbite (A Cautionary Tale)”, in Women's Studies Quarterly, volume 33, number 3/4, page 403