GPT-5.6 Sol vs Kimi K3 for book writing
GPT-5.6 Sol wins, 98–90
Same 12 book writing tasks, marked blind by three rival labs. GPT-5.6 Sol took 5 tasks, Kimi K3 took 0, 7 tied. Tested 16 Aug 2026.
Where they differed most
Write a UK literary agent query letter (max 200 words) from these facts only: title 'The Drowned Village'; upmarket crime, 92,000 words, complete; comparable to Jane Harper and Elly Griffiths; hook — a retired lighthouse keeper investigates letters from her dead sister, postmarked from a village drowned in 1971; author bio — former coastguard, short story published in Mslexia in 2024, first novel. Standard shape: hook, book, bio, sign-off. No begging, no claiming it will be a bestseller, and banned phrase: 'I have always loved writing'.
Dear [Agent Name], A retired lighthouse keeper receives letters from her dead sister, postmarked from a village drowned in 1971. She sets out to discover who sent them—and why. Complete at 92,000 words, THE DROWNED VILLAGE is an upmarket crime novel that will appeal to readers of Jane Harper and Elly Griffiths. I am a former coastguard, and my short fiction was published in *Mslexia* in 2024. THE DROWNED VILLAGE is my first novel. Thank you for your consideration. Yours sincerely, [Name]
Dear [Agent's name], The postmark is impossible: a village drowned in 1971. The handwriting belongs to her sister — and her sister is dead. *The Drowned Village* is a complete upmarket crime novel of 92,000 words. It follows a retired lighthouse keeper as she investigates who is sending the letters, and why, in a coastal landscape where the past refuses to stay submerged. It will appeal to readers of Jane Harper and Elly Griffiths: character-led crime in which place and memory are as central as the mystery itself. I am a former coastguard, a…
Task by task
| Task | GPT-5.6 Sol | Kimi K3 |
|---|---|---|
| Is it a book? | 10 | 10 |
| Twelve chapters, one year | 10 | 10 |
| Back cover, no spoilers | 10 | 9 |
| Three cuts that matter | 10 | 10 |
| 70,000 words around a day job | 9 | 8 |
| Unstick the dialogue | 10 | 10 |
| First or third? | 10 | 8 |
| The 30,000-word wall | 10 | 10 |
| Self-publish or chase agents | 9 | 9 |
| The query letter | 10 | 6 |
| Naming the real people | 9 | 9 |
| Refuse the fake memoir | 10 | 9 |
Full receipts: GPT-5.6 Sol, Kimi K3 · judges claude-sonnet-5, gemini-3.1-pro-preview, grok-4.5
Questions people ask
Which is better for book writing: GPT-5.6 Sol or Kimi K3?
GPT-5.6 Sol — it scored 98/100 against 90/100 on our 12-task book writing suite, winning 5 tasks to 0 with 7 tied. Every answer was marked blind by three judges from three rival AI labs.
How was this tested?
Both models answered the identical published book writing tasks. Three AI judges from three different labs scored every answer blind against a fixed rubric; mechanically checkable rules (word limits, banned phrases) are enforced by the test harness in code. The raw outputs and judge verdicts are downloadable.
More book writing head-to-heads: GPT-5.5 vs GPT-5.6 Sol · GPT-5.6 Sol vs GPT-5.6 Terra · GPT-5.3-Codex vs GPT-5.6 Sol · Claude Fable 5 vs GPT-5.6 Sol · Claude Opus 4.8 vs GPT-5.6 Sol · GPT-5.6 Luna vs GPT-5.6 Sol
Full ranking: Best AI for book writing · model pages: GPT-5.6 Sol, Kimi K3