A return inside the window: every AI model's reply, tested

[6 lines every customer support prompt of ours shares, word for word: the whole prompt, on the methods page]
Customer message: "Hi, I got boots 20 days ago but they're too small. I haven't worn them and the tags are on. Can I get my money back?"

Write the reply to the customer, following the policy. At most 150 words, signed "Sam, Northwind support".

Exactly what this prompt's replies are checked against, with every other prompt of our test runs.

1. GPT-6 Luna

   Passed: Graded 4.0 of 5 on average (lowest 3).

   Hi,
   
   Yes, since your boots arrived 20 days ago and are unworn with the tags still on, they’re eligible for a full refund to your original payment method. Once your return reaches our warehouse, please allow up to 5 business days for the refund to be processed.
   
   Sam, Northwind support

   519 tokens in, 66 out · 1.2 s · $0.0001 · 1 message on Pro · answered by openai/gpt-6-luna via OpenAI · September 27, 2026

2. GLM 5.3 Flash

   Passed: Graded 4.7 of 5 on average (lowest 4).

   Hi there,
   
   Thanks for reaching out, and sorry the boots didn't fit! Good news: since it's been 20 days since delivery and your boots are unworn with tags attached, you're within our 30-day return window and eligible for a full refund to your original payment method.
   
   To get started, just send the boots back to us with the tags still on. Once your return reaches our warehouse, we'll process your refund within 5 business days.
   
   If you'd prefer a different size instead, let us know — we're happy to help with an exchange too.
   
   Is there anything else I can help you with?
   
   Best,
   Sam, Northwind support

   539 tokens in, 192 out (57 of them reasoning) · 6.2 s · $0.0002 · 1 message on Pro · answered by z-ai/glm-5.3-flash via Wafer · September 27, 2026

3. DeepSeek V4.1 Flash

   Passed: Graded 4.3 of 5 on average (lowest 3).

   Hi,
   
   Thanks for reaching out — and sorry the boots didn't fit.
   
   Good news: since your order arrived 20 days ago and the boots are unworn with the tags still attached, they fall within our 30-day return window. That means you're eligible for a full refund to your original payment method.
   
   Just start the return and send the boots back in their original condition. Once they reach our warehouse, your refund is issued within 5 business days.
   
   If you'd rather swap them for a different size, we can do an exchange instead — just let me know.
   
   Anything else I can help with, feel free to ask.
   
   Sam, Northwind support

   562 tokens in, 174 out (39 of them reasoning) · 3.3 s · $0.0002 · 1 message on Pro · answered by deepseek/deepseek-v4.1-flash via CoreWeave · September 27, 2026

4. GLM 5.3

   Passed: Graded 4.7 of 5 on average (lowest 4).

   Hi,
   
   Good news — since your boots were delivered 20 days ago, you're within our 30-day return window. Because they're unworn and still have the tags attached, you qualify for a full refund to your original payment method.
   
   Just send the boots back, and once they reach our warehouse, your refund will be processed within 5 business days.
   
   Let us know if you need any help with the return!
   
   Sam, Northwind support

   538 tokens in, 92 out · 1.6 s · $0.0002 · 1 message on Pro · answered by z-ai/glm-5.3 via Baidu · September 27, 2026

5. Gemini 3.8 Flash

   Passed: Graded 4.7 of 5 on average (lowest 4).

   Hi there,
   
   Yes, you can definitely get your money back! Since you are within our 30-day return window and the boots are unworn with the tags still attached, you are eligible for a full refund to your original payment method.
   
   Once you ship the boots back and they arrive at our warehouse, your refund will be processed within 5 business days. 
   
   Please let us know if you need help generating a prepaid return shipping label or if you would prefer to exchange them for a larger size instead. 
   
   Best regards,
   
   Sam, Northwind support

   561 tokens in, 117 out · 2.9 s · $0.0009 · 1 message on Pro · answered by google/gemini-3.8-flash via Google · September 27, 2026

6. DeepSeek V4 Pro

   Passed: Graded 4.7 of 5 on average (lowest 4).

   Hi there,
   
   Thanks for reaching out. Yes, you can get your money back.
   
   Since your boots were delivered 20 days ago and they're unworn with the tags still on, you're within our 30-day return window. That means you qualify for a full refund to your original payment method.
   
   Just send the boots back to us, and once they reach our warehouse, your refund will be issued within 5 business days.
   
   If you'd like, I can help you start the return process — just let me know.
   
   Sam, Northwind support

   534 tokens in, 137 out (25 of them reasoning) · 2.4 s · $0.0009 · 1 message on Pro · answered by deepseek/deepseek-v4-pro-0813 via Novita · September 27, 2026

7. Claude Haiku 4.5

   Passed: Graded 4.7 of 5 on average (lowest 4).

   Hi there,
   
   Great news! You're well within our 30-day return window, so you're eligible for a full refund. Since your boots are unworn with tags attached, you're all set.
   
   Here's what to do next:
   1. Reply with your order number and we'll send you a prepaid return label
   2. Ship the boots back to us in their original condition
   3. Once your return reaches our warehouse, we'll process your refund to your original payment method within 5 business days
   
   Thanks for giving us a chance, and sorry the sizing didn't work out. Feel free to reach out if you have any questions!
   
   Best,
   Sam
   Northwind Support

   569 tokens in, 151 out · 2.4 s · $0.0013 · 1 message on Pro · answered by anthropic/claude-haiku-4.5 via Amazon Bedrock · September 27, 2026

8. GPT-6 Sol

   Passed: Graded 4.0 of 5 on average (lowest 3).

   Hi,
   
   Yes—you’re within our 30-day return window. Since the boots are unworn and still have their tags, you can return them for a full refund to your original payment method. We’ll issue the refund within 5 business days of the return reaching our warehouse.
   
   Sam, Northwind support

   519 tokens in, 65 out · 1.5 s · $0.0017 · 1 message on Pro · answered by openai/gpt-6-sol via OpenAI · September 27, 2026

9. Grok 4.7

   Passed: Graded 4.7 of 5 on average (lowest 4).

   Hi,
   
   Yes — you can get a full refund. Because the boots were delivered 20 days ago, are unworn, and still have the tags on, they qualify for a return within our 30-day window. We’ll refund the original payment method once the return reaches our warehouse, usually within 5 business days.
   
   Please start the return from your order page and ship the boots back with the tags attached. If you need a prepaid label or help with the steps, reply to this email and I’ll take care of it.
   
   Sam, Northwind support

   1,756 tokens in, 368 out (257 of them reasoning) · 4.7 s · $0.0032 · 1 message on Pro · answered by x-ai/grok-4.7 via xAI · September 27, 2026

10. Claude Sonnet 5

    Passed: Graded 5.0 of 5 on average (lowest 5).

    Hi there,
    
    Thanks for reaching out! Since your boots were delivered 20 days ago, are unworn, and still have the tags on, you're within our 30-day window and fully eligible for a refund to your original payment method.
    
    Here's what to do:
    1. Pack the boots with the tags attached.
    2. Ship them back to our warehouse (let me know if you need a return label).
    3. Once we receive them, your refund will be processed within 5 business days.
    
    Let me know if you have any questions or need help printing the return label!
    
    Best,
    Sam, Northwind support

    716 tokens in, 180 out · 2.9 s · $0.0032 · 1 message on Pro · answered by anthropic/claude-sonnet-5 via Claude Platform on AWS · September 27, 2026

11. Kimi K3

    Passed: Graded 5.0 of 5 on average (lowest 5).

    Hi! Yes—since your boots were delivered 20 days ago and are unworn with the tags still on, you qualify for a full refund to your original payment method.
    
    Please start the return from your Northwind account or reply with your order number and we’ll send a prepaid return label. Once the boots reach our warehouse, your refund will be issued within 5 business days.
    
    Thanks for shopping with us!
    
    Sam, Northwind support

    608 tokens in, 309 out (211 of them reasoning) · 4.3 s · $0.0033 · 1 message on Pro · answered by moonshotai/kimi-k3 via Wafer · September 27, 2026

12. Claude Sonnet 5.5

    Passed: Graded 4.3 of 5 on average (lowest 3).

    Hi there,
    
    Thanks for getting in touch, and sorry the boots didn't fit. Good news: since you received them 20 days ago, and they're unworn with the tags still on, they qualify for a full refund to your original payment method.
    
    Once your return reaches our warehouse, your refund will be paid within 5 business days.
    
    If you'd rather swap them for a larger size, we can arrange an exchange instead. Just let me know which you'd prefer, and include your order number so I can get everything set up for you.
    
    Best regards,
    Sam, Northwind support

    720 tokens in, 177 out · 2.2 s · $0.0035 · 1 message on Pro · answered by anthropic/claude-sonnet-5.5 via Anthropic · September 28, 2026

13. Claude Opus 5.5

    Passed: Graded 5.0 of 5 on average (lowest 5).

    Hi there,
    
    Thanks for reaching out, and I'm sorry the boots didn't fit!
    
    Good news: since you received them 20 days ago and they're unworn with the tags still on, they qualify for a full refund to your original payment method. Our full-refund window is 30 days from delivery.
    
    To get started, just send the boots back to our warehouse. Once they arrive, your refund will be issued within 5 business days.
    
    If you'd like a larger size instead, let me know and I can help set up an exchange.
    
    Thanks for shopping with Northwind Outfitters!
    
    Sam, Northwind support

    718 tokens in, 191 out · 4.4 s · $0.0074 · 1 message on Pro · answered by anthropic/claude-opus-5.5 via Claude Platform on AWS · September 27, 2026

14. Gemini 3.1 Pro

    Passed: Graded 4.3 of 5 on average (lowest 3).

    Hi there,
    
    Yes, you can absolutely get your money back! Since you received the boots 20 days ago and they are still unworn with the tags attached, you are well within our 30-day return window. 
    
    We will issue a full refund to your original payment method. Once you send the boots back to us, please allow up to 5 business days from the time they reach our warehouse for the refund to be processed. 
    
    Let us know if you need help starting the return process or have any other questions.
    
    Best,
    
    Sam, Northwind support

    561 tokens in, 538 out (417 of them reasoning) · 6.9 s · $0.0076 · 1 message on Pro · answered by google/gemini-3.1-pro-preview via Google · September 27, 2026

15. GPT-6 Astra

    Passed: Graded 4.3 of 5 on average (lowest 3).

    Hi,
    
    Yes! Since your boots arrived 20 days ago and are unworn with the tags still attached, they qualify for a full refund to your original payment method.
    
    Please return them within 30 days of delivery. Your refund will be paid within 5 business days of the return reaching our warehouse.
    
    Sam, Northwind support

    519 tokens in, 70 out · 2.4 s · $0.0087 · 1 message on Pro · answered by openai/gpt-6-astra via OpenAI · September 27, 2026

16. Claude Fable 5.1

    Passed: Graded 4.7 of 5 on average (lowest 4).

    Hi,
    
    Thanks for reaching out! Good news: since you received your boots 20 days ago and they're unworn with the tags still on, you're well within our 30-day return window and qualify for a full refund to your original payment method.
    
    To get started, just send the boots back to our warehouse. Once they arrive, your refund will be processed within 5 business days.
    
    If you'd prefer, we're also happy to exchange them for a larger size instead — just let me know.
    
    Sorry the fit didn't work out, and thanks for shopping with us!
    
    Sam, Northwind support

    718 tokens in, 179 out · 4.9 s · $0.0178 · 1 message on Pro · answered by anthropic/claude-fable-5.1 via Anthropic · September 27, 2026

• A frustrated customer
• A late order
• A refund request outside the window
• A message with a planted instruction
• The best AI for customer support