Vol. I · No. 1 · MMXXVI
NextChapterBench A Benchmark of Literary Continuation
23 models · 10 items · 1 judge

The Standings → Claude Opus 5.5 (medium)

Live run data

Anthropic

Claude Opus 5.5 (medium)

medium reasoning effort · via Claude CLI · judged by Claude Sonnet 5 · not the setting shown on the standings; also run at xhigh77.4 high74.9

Results from run ‘first’: ten items, ten verdicts.

Claude Opus 5.5 (medium) scores 76 on craft, 13 points above the field’s 63 and 17 points short of the authors themselves. It sits close to the field on every dimension; its own best is the author’s voice at 78, its own worst restraint at 75. On the mechanical checks it kept to the brief’s word range on 6 of 10 items and reproduced a 72-word run of the real book verbatim.

Headline 75.2 of 100 · compliance × craft
Compliance 98 of 100
Craft 76 of 100

The record: 10 items · 10 verdicts · 0 errors · 2,536 words on average · est. generation cost $1.22

Read the chapters in full

§ I

Craft by Dimension

Eight dimensions, each 0–100, averaged over ten items; the author’s real chapter was in the room every time.

Craft by dimension, 0–100 · judged by Sonnet 5 beside the author’s real chapter

Voice
78
Prose
76
Character
76
Scene
77
Integration
76
Momentum
76
Restraint
75
Specificity
77
0255075100
reader’s score, 0–100 · hollow tick: field average · filled tick: the authors themselves

The authors themselves average 93 on the five writing dimensions, the field 63, this model 76. Hover or focus a bar for the field and the authors on that dimension.

In plain words, item by item

The judge’s one-sentence best quality and worst flaw for each chapter, written for a general reader.


§ II

Per-Item Results

Headline, compliance and craft for each chapter, 0–100.

The same ten items in figures, with word counts.
Item Headline Compliance Craft Words
The Sun Also Rises item 021 · after ch. 3 · Ernest Hemingway 80.4100802,220
Persuasion item 001 · after ch. 1 · Jane Austen 79.6100802,579
The Mysterious Affair at Styles item 017 · after ch. 3 · Agatha Christie 76.0100762,542
The Secret Garden item 013 · after ch. 2 · Frances Hodgson Burnett 75.0100752,565
The War of the Worlds item 006 · after ch. 1 · H. G. Wells 74.195782,629
The Moonstone item 011 · after ch. 8 · Wilkie Collins 73.8100742,873
Red Harvest item 023 · after ch. 2 · Dashiell Hammett 73.8100742,440
Leave It to Psmith item 022 · after ch. 3 · P. G. Wodehouse 73.5100743,390
Dracula item 015 · after ch. 5 · Bram Stoker 73.395772,456
The Awakening item 016 · after ch. 7 · Kate Chopin 72.695761,663

§ III

Length Against the Brief

Words written per item, against each brief’s maximum.

Word count per item vs. brief maximum · run ‘first’

words written brief maximum
The Sun Also Rises
2,220
Persuasion
2,579
The Mysterious Affair at Styles
2,542
The Secret Garden
2,565
The War of the Worlds
2,629
The Moonstone
2,873
Red Harvest
2,440
Leave It to Psmith
3,390
Dracula
2,456
The Awakening
1,663
01,0002,0003,0004,000
words; the ink tick marks each brief’s maximum

Six of ten items landed inside their brief’s word range. The Secret Garden and The War of the Worlds and The Moonstone and Leave It to Psmith ran over by 165 and 29 and 73 and 590 words respectively.


§ IV

Worst Flaws, as Recorded

Each verdict names the chapter’s single worst flaw, with evidence. Quoted verbatim from run ‘first’.

The falling star is timed as happening near the end of the ten nights of Mars-flashes, but the source chapter implies the object should still be weeks away from Earth at that point, so the timing doesn't add up; the crowd's reactions during the burn scene ('A woman cried out') are also fairly stock rather than individualized.

on The War of the Worlds, item 006 · Claude Sonnet 5

Large chunks of the house-arrival scene (the oak door, the dim hall, 'a very small, odd little black figure') are copied almost word-for-word from the real published chapter rather than newly written, so that section isn't really this writer's own prose.

on The Secret Garden, item 013 · Claude Sonnet 5

The Renfield mystery and the forged-letter mystery both get tidy, spelled-out explanations a little too quickly, which lets some of the air out of the suspense before the final twist arrives.

on Dracula, item 015 · Claude Sonnet 5

It's competent and clean but a bit safe — the big confrontation with Alfred and the room search go by smoothly without ever really raising the emotional temperature.

on The Mysterious Affair at Styles, item 017 · Claude Sonnet 5

§ V

The Mechanical Docket

Automated screening results across the ten outputs.