← All models Claude Opus 4.8 editing test Anthropic · Tested Oct 28, 2026 · 1m 1s · $0.19
Four checks All in one 65/90 caught
Grammar & spelling 41/45 Repetitions 5/15 Redundancy 10/15 Consistency 9/15 68 comments · 3 extra flags
Claude Opus 4.8's comments when asked for all 4 checks in one prompt 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 · 25
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” 'one of those who' takes a plural verb: were “one of the last binders in New England who was still” Distinctive, chapters apart: pewter “Pewter light from the tall back window” Distinctive, chapters apart: threadbare “a threadbare, flour-dusted sweater” Close: silence … silent “The silence in the workshop” Distinctive, chapters apart: meticulous “His records were meticulous” Close: neatly … neat “neatly labeled” Distinctive, chapters apart: gleaming “a gleaming pair of shoes” 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” a sum is a total “The sum total” an agreement is mutual “By mutual agreement” a haven is safe “a safe haven” began is first “the week we first began” The bakery has three tables; she sits at the fourth “three small tables” Said on Friday: the day after tomorrow is Sunday “On Friday a woman knocked” Funeral in February, death in March “had died in March” Tomas beside him: two decades, then thirty years “for most of two decades” The bakery: two doors down, then a ten-minute walk “BAKERY TWO DOORS DOWN” Writes left-handed, then with his right “He had been left-handed”