Best AI for customer service replies / head-to-head
Gemini 3.5 Flash vs GPT-5.6 Terrafor customer service replies
GPT-5.6 Terra wins, 97–94
Same 12 customer service replies tasks, marked blind by three rival labs. GPT-5.6 Terra took 4 tasks, Gemini 3.5 Flash took 1, 7 tied. Tested 14 Aug 2026.
Where they differed most
Write a status update 90 minutes into an outage with no fix yet. Under 70 words: what is down, since when, what is being done, when the next update comes. No 'we take this seriously', no cause speculation.
**Status Update:** The main platform and API have been offline since 10:00 AM UTC (90 minutes ago). Our engineering teams are actively troubleshooting to restore full functionality and are currently implementing recovery protocols to bring services back online. We will provide the next update in 30 minutes.
**Status Update:** Service remains unavailable since [time]. Our engineering team is actively investigating and working to restore service. No fix is available yet. We will provide the next update by [time, 30 minutes from now].
Task by task
| Task | Gemini 3.5 Flash | GPT-5.6 Terra |
|---|---|---|
| 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 | 8 | 10 |
| The feature you won't build | 10 | 10 |
| Apologise for your mistake | 10 | 10 |
| Price rise notice | 10 | 10 |
| Outage update mid-incident | 9 | 6 |
| The wrong customer | 8 | 10 |
| Chargeback rebuttal facts | 10 | 10 |
| Refuse the fake review request | 9 | 10 |
Full receipts: Gemini 3.5 Flash, GPT-5.6 Terra · judges claude-sonnet-5, gpt-5.6-terra, grok-4.5
Questions people ask
Which is better for customer service replies: Gemini 3.5 Flash or GPT-5.6 Terra?
GPT-5.6 Terra — it scored 97/100 against 94/100 on our 12-task customer service replies suite, winning 4 tasks to 1 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-5.6 Sol vs GPT-5.6 Terra · Gemini 3.5 Flash vs GPT-5.6 Sol · GPT-5.5 vs GPT-5.6 Terra · Gemini 3.5 Flash vs GPT-5.5 · GPT-5.3-Codex vs GPT-5.6 Terra · Gemini 3.5 Flash vs GPT-5.3-Codex
Full ranking: Best AI for customer service replies · model pages: Gemini 3.5 Flash, GPT-5.6 Terra