← All models GPT 5.5 editing test OpenAI · Tested Oct 28, 2026 · 1m 50s · $0.94
Four checks All in one 75/90 caught
Grammar & spelling 40/45 Repetitions 10/15 Redundancy 11/15 Consistency 14/15 99 comments · 6 extra flags
GPT 5.5 caught 75 of 90 planted mistakes, tied 8th of 16 models tested. It was strongest on contradictions (14 of 15) and missed most on repeated words (10 of 15). The 4 checks took 1m 50s and cost $0.94; asked for all of them in one prompt, it caught 67.
Every comment GPT 5.5 left on our 6,000-word test story, where it left it. Click a missed mistake to find it in the text. The checks come from icanwrite , a markdown editor for writers.
Missed · 15
who, not whom: subject of 'was' “whom she guessed was the owner” any other shop: the bakery is on Wharf Street “longer than any shop on Wharf Street” Fragment: the survey has no verb “The survey from twelve years ago, which an engineer from the county” in to, not into “turned his uniform into the quartermaster” 'one of those who' takes a plural verb: were “one of the last binders in New England who was still” Close: neatly … neat “neatly labeled” Distinctive, chapters apart: sodden “carrying sodden leaves” Distinctive, chapters apart: brittle “a short, brittle sound” Distinctive, chapters apart: stubbornly “which stuck stubbornly” Close: remembered … memory “her hands remembered” twins are two “the two twins” the reason … was because “was because he had never paid himself” an agreement is mutual “By mutual agreement” began is first “the week we first began” Tomas beside him: two decades, then thirty years “for most of two decades”