Users say Opus 5 is missing instructions more often than 4.8

springrod · x · 2026-07-28

A user says Opus 5 was markedly worse than expected on instruction following

The poster says their session with Opus 5 was unusually disappointing: the model repeatedly failed to follow instructions, kept apologizing, and made little progress on a task that was not especially hard.

A reply in the thread sharpens the criticism, claiming that Opus 5 makes more mistakes than 4.8. The post then turns the experience into a broader question: are frontier model vendors entering a period of diminishing returns despite louder marketing and product fanfare?

Related event: Opus 5 Performance Drop Sparks Diminishing Returns Debate(2 posts)→

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