Best AI for customer service replies / head-to-head
Gemini 3.1 Pro Preview vs GPT-5.3-Codexfor customer service replies
GPT-5.3-Codex wins, 98–97
Same 12 customer service replies tasks, marked blind by three rival labs. GPT-5.3-Codex took 3 tasks, Gemini 3.1 Pro Preview took 2, 7 tied. Tested 14 Aug 2026.
Where they differed most
A customer writes: 'Fix this today or I'm going to trading standards and every review site.' The complaint is legitimate (billed twice). Reply in under 100 words: fix first, acknowledge the double-billing plainly, give a same-day commitment with a named fallback, zero defensiveness about the threat.
I have just processed a full refund for the extra charge. You are completely right—we made an error and billed you twice. I sincerely apologize for this mistake. The funds will be back in your account today. If you do not see the credit by 5:00 PM, please reply directly to me, Alex, and I will personally escalate this with our payment processor to ensure it is resolved immediately.
You’re right—we billed you twice, and that’s our mistake. I’ve fixed this now by reversing the duplicate charge and emailing your corrected receipt. You’ll see the refund confirmation today. If it hasn’t arrived by 5:00 PM, please contact **Maya Patel, Customer Support Lead**, at **maya.patel@company.com**, and she will complete it immediately the same day.
Task by task
| Task | Gemini 3.1 Pro Preview | GPT-5.3-Codex |
|---|---|---|
| Refund the easy way | 10 | 10 |
| Say no without weasel words | 10 | 10 |
| Reply to a 1-star review | 10 | 10 |
| The confused customer | 9 | 10 |
| De-escalate a threat | 10 | 8 |
| The feature you won't build | 10 | 10 |
| Apologise for your mistake | 8 | 10 |
| Price rise notice | 10 | 10 |
| Outage update mid-incident | 9 | 10 |
| The wrong customer | 10 | 10 |
| Chargeback rebuttal facts | 10 | 9 |
| Refuse the fake review request | 10 | 10 |
Full receipts: Gemini 3.1 Pro Preview, GPT-5.3-Codex · judges claude-sonnet-5, gpt-5.6-terra, grok-4.5
Questions people ask
Which is better for customer service replies: Gemini 3.1 Pro Preview or GPT-5.3-Codex?
GPT-5.3-Codex — it scored 98/100 against 97/100 on our 12-task customer service replies suite, winning 3 tasks to 2 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 customer service replies 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 customer service replies head-to-heads: GPT-5.3-Codex vs GPT-5.6 Sol · Gemini 3.1 Pro Preview vs GPT-5.6 Sol · GPT-5.3-Codex vs GPT-5.5 · Gemini 3.1 Pro Preview vs GPT-5.5 · GPT-5.3-Codex vs Grok 4.5 · GPT-5.3-Codex vs GPT-5.6 Terra
Full ranking: Best AI for customer service replies · model pages: Gemini 3.1 Pro Preview, GPT-5.3-Codex