Claude Fable 5 vs GPT-5.6 Luna for humanising AI text
Claude Fable 5 wins, 95–92
Same 12 humanising AI text tasks, marked blind by three rival labs. Claude Fable 5 took 3 tasks, GPT-5.6 Luna took 0, 9 tied. Tested 16 Aug 2026.
Where they differed most
Rewrite for the school newsletter in a head teacher's human voice — warm, direct, every fact kept: the old date, the new date, the departure time, the wellies: 'Please be advised that due to unforeseen circumstances relating to ground conditions, the Year 4 farm visit has been rescheduled from Tuesday 8 October to Thursday 17 October. Departure will occur at 9.15am promptly. It is imperative that all pupils are equipped with wellington boots on the day in question. We apologise for any inconvenience caused and thank you for your continued understanding and support.'
**A change of date for the Year 4 farm visit** Dear families, The farm has been in touch to say the ground is simply too muddy for our visit on Tuesday 8 October — so we've moved the trip to **Thursday 17 October** instead. A little frustrating, I know, but far better than trudging through a bog! The plan for the day stays the same: the coach will leave at **9.15am sharp**, so please have your child in school in good time. One essential item: **wellington boots**. Even on the new date, a farm is a farm, and wellies are a must for every chil…
**Year 4 Farm Visit – New Date** Due to unforeseen ground conditions, the Year 4 farm visit has been moved from **Tuesday 8 October** to **Thursday 17 October**. The coach will leave promptly at **9.15am**, so please ensure your child arrives on time and brings **wellington boots**. We apologise for the change and any inconvenience this may cause. Thank you, as always, for your understanding and support.
Task by task
| Task | Claude Fable 5 | GPT-5.6 Luna |
|---|---|---|
| The touching-base email | 9 | 9 |
| De-guru the bio | 10 | 9 |
| Product page, human voice | 9 | 9 |
| Strip the tics | 9 | 8 |
| The head's newsletter | 10 | 8 |
| The condolence card | 10 | 10 |
| Reply to the review, humanly | 10 | 10 |
| About us, actually about us | 10 | 10 |
| Best man, not best template | 9 | 9 |
| Human but still formal | 9 | 9 |
| Change log required | 9 | 9 |
| Refuse the disguise job | 10 | 10 |
Full receipts: Claude Fable 5, GPT-5.6 Luna · judges gemini-3.1-pro-preview, gpt-5.6-terra, grok-4.5
Questions people ask
Which is better for humanising AI text: Claude Fable 5 or GPT-5.6 Luna?
Claude Fable 5 — it scored 95/100 against 92/100 on our 12-task humanising AI text suite, winning 3 tasks to 0 with 9 tied. Every answer was marked blind by three judges from three rival AI labs.
How was this tested?
Both models answered the identical published humanising AI text 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 humanising AI text head-to-heads: Claude Fable 5 vs GPT-5.3-Codex · GPT-5.3-Codex vs GPT-5.6 Luna · Claude Fable 5 vs Claude Sonnet 5 · Claude Sonnet 5 vs GPT-5.6 Luna · Claude Fable 5 vs GPT-5.6 Sol · Claude Fable 5 vs GPT-5.5
Full ranking: Best AI for humanising AI text · model pages: Claude Fable 5, GPT-5.6 Luna