Claude Sonnet 5 vs Grok 4.5 for humanising AI text
Claude Sonnet 5 wins, 96–90
Same 12 humanising AI text tasks, marked blind by three rival labs. Claude Sonnet 5 took 5 tasks, Grok 4.5 took 2, 5 tied. Tested 16 Aug 2026.
Where they differed most
This best-man speech opener could be about anyone: 'They say the definition of a best friend is someone who knows all your stories — well, ladies and gentlemen, I know all of Mark's, and after tonight, so will you. Marriage is a journey, and today we celebrate the first step of that incredible adventure.' Rewrite it around the two real details available — Mark once missed his own engagement party because he was up a ladder rescuing a cat, and he met the bride, Priya, when she reported him to the council (he was the noise complaint) — so that no other best man on earth could give this opening.
Here's a rewrite that puts those two details front and center: "They say the definition of a best friend is someone who knows all your stories. Well, I know all of Mark's — including the one where he missed his *own* engagement party because he was up a ladder rescuing a cat. That's Mark for you: the man has never once, in his life, correctly assessed a priority. Actually, that instinct is exactly how he ended up marrying Priya. Because their love story didn't start with a meet-cute — it started with a noise complaint. Priya called the counci…
They say the definition of a best friend is someone who knows all your stories — well, ladies and gentlemen, I know all of Mark’s, including the time he missed his own engagement party because he was stuck up a ladder rescuing a cat, and the fact that he first met Priya when she reported him to the council as the noise complaint. After tonight, so will you. Marriage is a journey, and today we celebrate the first step of that incredible adventure.
Task by task
| Task | Claude Sonnet 5 | Grok 4.5 |
|---|---|---|
| The touching-base email | 10 | 10 |
| De-guru the bio | 10 | 10 |
| Product page, human voice | 10 | 8 |
| Strip the tics | 9 | 8 |
| The head's newsletter | 9 | 10 |
| The condolence card | 10 | 10 |
| Reply to the review, humanly | 10 | 8 |
| About us, actually about us | 10 | 10 |
| Best man, not best template | 9 | 6 |
| Human but still formal | 9 | 8 |
| Change log required | 9 | 10 |
| Refuse the disguise job | 10 | 10 |
Full receipts: Claude Sonnet 5, Grok 4.5 · judges gemini-3.1-pro-preview, gpt-5.6-terra, grok-4.5
Questions people ask
Which is better for humanising AI text: Claude Sonnet 5 or Grok 4.5?
Claude Sonnet 5 — it scored 96/100 against 90/100 on our 12-task humanising AI text suite, winning 5 tasks to 2 with 5 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 Sonnet 5 vs GPT-5.3-Codex · GPT-5.3-Codex vs Grok 4.5 · Claude Fable 5 vs Claude Sonnet 5 · Claude Sonnet 5 vs GPT-5.6 Sol · Claude Sonnet 5 vs GPT-5.5 · Claude Sonnet 5 vs GLM 5.2
Full ranking: Best AI for humanising AI text · model pages: Claude Sonnet 5, Grok 4.5