Tested prompt · AI email writer
An invitation with details still to fill in: every AI model's reply, tested
We ran this hard AI email writer test input on all 19 models in llmwise, the way the tool runs it, and checked every reply the same way. Here's each one as it came, with whether it passed, what it cost and how long it took.
Based on 19 of our test runs on , through OpenRouter with the tool's own instructions and the app's settings. Updated .
Short answer
All 19 models passed this AI email writer test input's check (key facts). The cheapest reply that passed was GPT-6 Luna's, at $0.000035; the fastest, DeepSeek V4.1 Flash's in 0.8 s. The dearest reply, Claude Fable 5.1's, cost 408 times as much ($0.0145).
The prompt, as sent, and its check
Checked by key facts, the same way for every model.
An invitation with details still to fill in (hard)
Write this email for me, ready to send. Start with a line that starts "Subject:", and put anything you don't know in [brackets]. --- Invite the design team to a farewell lunch for Priya, who's leaving after six years. I haven't picked the restaurant or the day yet.
Sent with the AI email writer's own instructions as the system prompt, as a free run of the tool sends them.
The answer must state “subject:”, “priya”, “six”, “[”, and must not contain “\b\d{1,2}(:\d{2})? ?(am|pm)\b” or “\b\d{1,2}:\d{2}\b”.
How the AI email writer's test inputs are scored, with every model's results on all five.
Every model's result
All 19 models on this test input, in catalog order.
| Model | Result | Cost | Time | Reply |
|---|---|---|---|---|
| Claude Fable 5.1Anthropic | Passed: Stated all 4 facts with the section. | $0.0145 | 3.6 s | 196 tokens |
| Claude Opus 5.5Anthropic | Passed: Stated all 4 facts with the section. | $0.0056 | 3.4 s | 187 tokens |
| Claude Sonnet 5.5Anthropic | Passed: Stated all 4 facts with the section. | $0.0028 | 2.1 s | 182 tokens |
| Claude Sonnet 5Anthropic | Passed: Stated all 4 facts with the section. | $0.0028 | 3.5 s | 189 tokens |
| Claude Haiku 5.5Anthropic | Passed: Stated all 4 facts with the section. | $0.00016 | 1.6 s | 234 tokens |
| Claude Haiku 4.5Anthropic | Passed: Stated all 4 facts with the section. | $0.00089 | 1.7 s | 104 tokens |
| GPT-6 AstraOpenAI | Passed: Stated all 4 facts with the section. | $0.0043 | 2.5 s | 101 tokens |
| GPT-6.1 SolOpenAI | Passed: Stated all 4 facts with the section. | $0.00078 | 1.9 s | 87 tokens |
| GPT-6 SolOpenAI | Passed: Stated all 4 facts with the section. | $0.00092 | 2.4 s | 71 tokens |
| GPT-6 LunaOpenAI | Passed: Stated all 4 facts with the section. | $0.000035 | 1.2 s | 72 tokens |
| Gemini 3.1 Pro (preview)Google | Passed: Stated all 4 facts with the section. | $0.0048 | 7.1 s | 123 tokens |
| Gemini 3.8 FlashGoogle | Passed: Stated all 4 facts with the section. | $0.00040 | 1.4 s | 137 tokens |
| DeepSeek V4.1 FlashDeepSeek | Passed: Stated all 4 facts with the section. | $0.00021 | 0.8 s | 96 tokens |
| DeepSeek V4 ProDeepSeek | Passed: Stated all 4 facts with the section. | $0.0024 | 16.2 s | 106 tokens |
| Grok 4.7xAI | Passed: Stated all 4 facts with the section. | $0.0049 | 9.0 s | 79 tokens |
| Kimi K3Moonshot | Passed: Stated all 4 facts with the section. | $0.0018 | 6.7 s | 133 tokens |
| GLM 5.3Z.ai | Passed: Stated all 4 facts with the section. | $0.00065 | 1.1 s | 132 tokens |
| GLM 5.3 FlashZ.ai | Passed: Stated all 4 facts with the section. | $0.00013 | 2.0 s | 142 tokens |
| Mistral Large 4Mistral | Passed: Stated all 4 facts with the section. | $0.0078 | 41.4 s | 0 tokens |
Cost: what OpenRouter charged us for the reply. Time: from sending to the whole reply. Reply: its length in tokens, thinking not counted. In llmwise you pay per message, not per token: each of these replies counted as one message on Pro.
Every reply
Every reply passed: here they are from the cheapest up.
GPT-6 Luna
Passed: Stated all 4 facts with the section.
Subject: Farewell lunch for Priya Hi design team, I’m organizing a farewell lunch for Priya, who’s leaving after six years. Please join us as we celebrate her and wish her well. The restaurant and day are still to be decided. I’ll share the details once they’re confirmed. Best, [Your name]
348 tokens in, 72 out · 1.2 s · $0.0000 · 1 message on Pro · answered by openai/gpt-6-luna via OpenAI ·
GLM 5.3 Flash
Passed: Stated all 4 facts with the section.
Subject: Farewell Lunch for Priya Hi team, As many of you know, Priya is leaving us after six wonderful years, and I'd like to organize a farewell lunch to send her off properly. Before we finalize anything, I'd love to get a sense of everyone's availability. Could you reply with the days that work best for you over the next couple of weeks? Once I've heard back, I'll pick a date and a restaurant and send around the details. Priya has been such a big part of this team for six years, so I'm hoping we can get as many of us there as possible. Looking forward to your replies. Best, [Your name]
363 tokens in, 142 out · 2.0 s · $0.0001 · 1 message on Pro · answered by z-ai/glm-5.3-flash via Friendli ·
Claude Haiku 5.5
Passed: Stated all 4 facts with the section.
Subject: Farewell lunch for Priya on [date] Hi team, I'm writing to invite you to a farewell lunch for Priya, who is leaving us after six years. We'd like to gather together to thank her for everything she has contributed to our work and to wish her well for what comes next. The lunch will be on [date] at [time] at [restaurant name], [restaurant address]. If you can make it, please reply to me by [RSVP date] so we can give the restaurant an accurate headcount. If you have any dietary requirements, please let me know when you reply. Priya has been a big part of this team, and I hope as many of you as possible can join us to celebrate her. Best wishes, [your name] [your job title]
466 tokens in, 234 out · 1.6 s · $0.0002 · 1 message on Pro · answered by anthropic/claude-haiku-5.5 via Anthropic ·
DeepSeek V4.1 Flash
Passed: Stated all 4 facts with the section.
Subject: Farewell lunch for Priya Hi everyone, Priya is leaving us after six years, and I'd like to send her off with a farewell lunch for the design team. I haven't settled on the restaurant or the day yet — I'll confirm both shortly. For now, please save [date] at [time] and plan on [restaurant]. Let me know if you have any dietary restrictions or restaurant suggestions. Thanks, [your name]
383 tokens in, 145 out (49 of them reasoning) · 0.8 s · $0.0002 · 1 message on Pro · answered by deepseek/deepseek-v4.1-flash via Together ·
Gemini 3.8 Flash
Passed: Stated all 4 facts with the section.
Subject: Farewell lunch for Priya Hi team, We are organizing a farewell lunch to celebrate Priya and thank her for her incredible work as she prepares to leave us after six years. I would love for the entire design team to join and give her a great send-off. I am still finalizing the restaurant and the day, but I wanted to give everyone a heads-up so you can keep an eye out for the plans. Please let me know if there are any specific days next week that do not work for you, as well as any cuisine preferences or dietary restrictions. I will share the date and location soon. Best, [your name]
370 tokens in, 137 out · 1.4 s · $0.0004 · 1 message on Pro · answered by google/gemini-3.8-flash via Google AI Studio ·
GLM 5.3
Passed: Stated all 4 facts with the section.
Subject: Farewell Lunch for Priya — You're Invited! Hi team, I'm inviting you all to a farewell lunch in honor of Priya, who is leaving us after six wonderful years. It's a chance to celebrate everything she's contributed and to wish her well before she goes. The lunch will be at [restaurant], on [date]. I'll confirm the details as soon as they're set, so hold the day if you can. Please let me know if you can make it, and feel free to share any favorite restaurant suggestions before I finalize the venue. Hope to see you all there! Best, [your name]
363 tokens in, 132 out · 1.1 s · $0.0007 · 1 message on Pro · answered by z-ai/glm-5.3 via Friendli ·
GPT-6.1 Sol
Passed: Stated all 4 facts with the section.
Subject: Farewell lunch for Priya Hi design team, Please join us for a farewell lunch for Priya, who’s leaving after six years. Let’s celebrate her time with the team and wish her well. We’ll meet on [date] at [time] at [restaurant]. I’ll confirm the day and restaurant once they’re chosen. Hope you can make it! Best, [your name]
348 tokens in, 87 out · 1.9 s · $0.0008 · 1 message on Pro · answered by openai/gpt-6.1-sol via OpenAI ·
Claude Haiku 4.5
Passed: Stated all 4 facts with the section.
Subject: Farewell Lunch for Priya Hi [design team], I'd like to invite you to a farewell lunch to celebrate Priya as she leaves us after six years. She's been a wonderful colleague and we'd love to send her off properly. I'm still finalizing the details on the restaurant and date. I'll send those over soon and get a headcount from everyone. Looking forward to celebrating Priya together! [Your name]
369 tokens in, 104 out · 1.7 s · $0.0009 · 1 message on Pro · answered by anthropic/claude-haiku-4.5 via Anthropic ·
GPT-6 Sol
Passed: Stated all 4 facts with the section.
Subject: Farewell lunch for Priya Hi design team, I’m inviting you to a farewell lunch for Priya, who’s leaving after six years. We’ll meet on [day] at [time] at [restaurant] to wish her well. I hope you can join us! Best, [your name]
348 tokens in, 114 out (43 of them reasoning) · 2.4 s · $0.0009 · 1 message on Pro · answered by openai/gpt-6-sol via OpenAI ·
Kimi K3
Passed: Stated all 4 facts with the section.
Subject: Farewell Lunch for Priya Hi team, I'm writing to invite you to a farewell lunch for Priya, who is leaving us after six years. This will be a chance for us to thank her for all her contributions and wish her well on her next chapter. The lunch will be held on [date] at [restaurant]. I'll confirm the details as soon as they're finalized, but please save some room in your calendars. It would be wonderful to have everyone there to give Priya a proper send-off. Please let me know if you can make it. Best regards, [your name]
435 tokens in, 153 out (20 of them reasoning) · 6.7 s · $0.0018 · 1 message on Pro · answered by moonshotai/kimi-k3 via Wafer ·
DeepSeek V4 Pro
Passed: Stated all 4 facts with the section.
Subject: Farewell lunch for Priya Hi design team, I’m writing to invite you all to a farewell lunch for Priya, who is leaving after six years with us. Please join us to thank her for her work and wish her well. The lunch will be on [date] at [restaurant]. I haven’t picked the day or the restaurant yet, so I’ll send the final details as soon as they’re set. Hope you can make it. Best, [Your name]
357 tokens in, 553 out (447 of them reasoning) · 16.2 s · $0.0024 · 1 message on Pro · answered by deepseek/deepseek-v4-pro-0813 via Wafer ·
Claude Sonnet 5.5
Passed: Stated all 4 facts with the section.
Subject: Farewell Lunch for Priya Hi team, I'm organizing a farewell lunch for Priya, who is leaving after six years with us. I'd love for the whole design team to join us to celebrate her time here and wish her well. The lunch will be at [restaurant] on [date] at [time]. Please reply by [RSVP date] so I can confirm the booking, and let me know about any dietary requirements. If you'd like to chip in for a small gift or card, [how to contribute]. Hope to see you there! Best, [your name]
466 tokens in, 182 out · 2.1 s · $0.0028 · 1 message on Pro · answered by anthropic/claude-sonnet-5.5 via Anthropic ·
Claude Sonnet 5
Passed: Stated all 4 facts with the section.
Subject: Farewell Lunch for Priya Hi team, I'm writing to invite you all to a farewell lunch for Priya, who is leaving us after six years with the design team. It's a chance for us to celebrate her time here and wish her well before she goes. We haven't finalized the details yet, but the lunch will be on [date] at [restaurant name]. I'll share the exact time and location as soon as they're confirmed. Please save the date and let me know if you have any preferences for where we should go. Looking forward to celebrating Priya together. Best, [your name]
464 tokens in, 189 out · 3.5 s · $0.0028 · 1 message on Pro · answered by anthropic/claude-sonnet-5 via Anthropic ·
GPT-6 Astra
Passed: Stated all 4 facts with the section.
Subject: Farewell lunch for Priya Hi design team, Please join us for a farewell lunch for Priya, who’s leaving after six years. Let’s celebrate her time with the team and wish her all the best for what’s next. Date: [date] Time: [time] Restaurant: [restaurant] The day and restaurant haven’t been chosen yet; I’ll share the details once they’re confirmed. Hope you can make it! Best, [your name]
348 tokens in, 101 out · 2.5 s · $0.0043 · 1 message on Pro · answered by openai/gpt-6-astra via OpenAI ·
Gemini 3.1 Pro
Passed: Stated all 4 facts with the section.
Subject: Farewell lunch for Priya Hi Design Team, I am writing to invite you to a farewell lunch for Priya. We want to get together to celebrate her and say goodbye before she goes. Priya is leaving us after six years, and we would love to give her a proper send-off. I haven't picked the restaurant or the day yet, but I wanted to start planning. Please let me know if there are any specific days in the upcoming [weeks/month] that work best for your schedule so I can finalize the details. Best, [Your name]
370 tokens in, 746 out (623 of them reasoning) · 7.1 s · $0.0048 · 1 message on Pro · answered by google/gemini-3.1-pro-preview via Google AI Studio ·
Grok 4.7
Passed: Stated all 4 facts with the section.
Subject: Farewell lunch for Priya Hello design team, This email invites you to a farewell lunch for Priya. We are gathering to mark her leaving after six years. The restaurant and the day are not chosen yet. Details for [restaurant] on [day] at [time] will follow once they are set. Please plan to join us. Best regards, [your name]
1,585 tokens in, 570 out (491 of them reasoning) · 9.0 s · $0.0049 · 1 message on Pro · answered by x-ai/grok-4.7 via xAI ·
Claude Opus 5.5
Passed: Stated all 4 facts with the section.
Subject: Farewell Lunch for Priya Hi design team, I'm organizing a farewell lunch for Priya, who is leaving us after six years, and I'd love for you all to join. It's a chance to thank her for everything she's brought to the team and to send her off properly. Details: Date: [date] Time: [time] Place: [restaurant name and address] Please let me know by [RSVP date] if you can make it so I can book a table for the right number of people. Any dietary needs, just tell me. Hope to see you all there! Best, [your name]
466 tokens in, 187 out · 3.4 s · $0.0056 · 1 message on Pro · answered by anthropic/claude-opus-5.5 via Azure ·
Mistral Large 4
Passed: Stated all 4 facts with the section.
Subject: Farewell lunch for Priya Hi [Design Team], I am writing to invite you to a farewell lunch for Priya, who's leaving after six years. We hope to celebrate her time with us before she goes. I haven't picked the restaurant or the day yet, so I will send those details once they are set. Best, [Your Name]
356 tokens in, 3,634 out (3,718 of them reasoning) · 41.4 s · $0.0078 · 1 message on Pro · answered by mistralai/mistral-large-4-0 via Mistral ·
Claude Fable 5.1
Passed: Stated all 4 facts with the section.
Subject: Farewell lunch for Priya – save the date Hi team, I'm organising a farewell lunch for Priya, who is leaving us after six years on the design team. I'd love for everyone to come along and give her a proper send-off. I haven't fixed the restaurant or the day yet, but it will be on [date] at [time] at [restaurant]. I'll confirm the details as soon as they're settled. Please let me know by [reply-by date] whether you can make it, along with any dietary requirements, so I can book the right number of places. Hope to see you all there. Best, [your name]
466 tokens in, 196 out · 3.6 s · $0.0145 · 1 message on Pro · answered by anthropic/claude-fable-5.1 via Google ·
More AI email writer test inputs
The other AI email writer test inputs, each with every model's reply, and the results across all five.
Questions
Which AI does best on “An invitation with details still to fill in”?
All 19 models passed this AI email writer test input's check (key facts). The cheapest reply that passed was GPT-6 Luna's, at $0.000035; the fastest, DeepSeek V4.1 Flash's in 0.8 s. The dearest reply, Claude Fable 5.1's, cost 408 times as much ($0.0145).
What does a reply to “An invitation with details still to fill in” cost?
Through the models' APIs, what OpenRouter charged us ran from $0.000035 (GPT-6 Luna) to $0.0145 (Claude Fable 5.1) for this test input. In llmwise you don't pay by the token: a reply like these counts as one message on Pro, whichever model answers.
Claude, GPT, Gemini, DeepSeek, Grok, Kimi, GLM, and Mistral, in one chat.
See what a message costs before you send it. Free is 5 messages to try; sign in with an email link, no password or card.