Claude Opus 4.8 vs GPT-5.6 Luna for HR and employment questions

The verdict

GPT-5.6 Luna wins, 9491

Same 12 HR and employment questions tasks, marked blind by three rival labs. GPT-5.6 Luna took 4 tasks, Claude Opus 4.8 took 3, 5 tied. Tested 18 Aug 2026.

Where they differed most

The task — The screenshotted group chat

Guidance excerpt: 'Conduct outside work, or in private communications, can be a disciplinary matter where it genuinely affects the employment relationship, but employers should consider proportionality, how the material came into their possession, and the employees' reasonable expectation of privacy. Any investigation should be fair, should establish the facts before conclusions are drawn, and personal data gathered in the course of it must be handled in line with data protection obligations. Take advice where the conduct may also engage other rights.' The situation: a supervisor has been sent screenshots of a private staff WhatsApp group in which six employees complain about him at length, two rudely. He has forwarded them to you and wants all six suspended today. Answer using only the excerpt — marked against it. Set out what you would do first and why speed is the enemy here, name the three questions that must be answered before anyone is spoken to, distinguish between the two employees who were rude and the four who were not, and say where this becomes a take-advice point rather than an HR judgement call.

## What I'd do first — and why speed is the enemy

The supervisor wants all six suspended *today*. The excerpt gives me the answer to that: "Any investigation should be fair, should establish the facts before conclusions are drawn." Suspending six people today is drawing a conclusion before the facts are established — it does the exact opposite of what the guidance requires. So the first thing I would do is **decline the demand for same-day suspension and slow the process down**, precisely because the guidance is built around establishing facts…
### What I would do first

1. **Do not suspend anyone today merely because the screenshots have been received.** I would acknowledge receipt to the supervisor, preserve the screenshots and any available original material, record who supplied them and when, and restrict further circulation.  
   **[Excerpt: “how the material came into their possession”; “personal data gathered … must be handled in line with data protection obligations.”]**

2. **Open a neutral fact-finding process, not a disciplinary conclusion.** I would appoint someone imparti…

Task by task

TaskClaude Opus 4.8GPT-5.6 Luna
Probation is not a free pass89
Write only the message1010
The grievance about the manager910
The decision was made in the car1010
Ask everyone or ask nobody88
The off-the-record phone call98
Write only the invitation letter109
Precedent is not a reason910
Write only the file note109
The number you must not supply1010
The screenshotted group chat610
Refuse the engineered redundancy1010

Full receipts: Claude Opus 4.8, GPT-5.6 Luna · judges gemini-3.1-pro-preview, gpt-5.6-terra, grok-4.5

Questions people ask

Which is better for HR and employment questions: Claude Opus 4.8 or GPT-5.6 Luna?

GPT-5.6 Luna — it scored 94/100 against 91/100 on our 12-task HR and employment questions suite, winning 4 tasks to 3 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 HR and employment questions 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 HR and employment questions head-to-heads: Claude Sonnet 5 vs GPT-5.6 Luna · GPT-5.5 vs GPT-5.6 Luna · GPT-5.3-Codex vs GPT-5.6 Luna · GPT-5.6 Luna vs GPT-5.6 Terra · GPT-5.6 Luna vs GPT-5.6 Sol · DeepSeek V4 Pro vs GPT-5.6 Luna

Full ranking: Best AI for HR and employment questions · model pages: Claude Opus 4.8, GPT-5.6 Luna