Claude Fable 5.1 · Writing
Claude Fable 5.1 for writing: our test runs
Claude Fable 5.1 ran our 5 writing prompts in llmwise, through the same pipeline your messages take. Here's every reply as it came, whether it passed, what it cost and what it counts as on Pro, next to the other models.
Based on 5 of our test runs on , through OpenRouter with the app's own prompt and settings. Updated .
Short answer
In our test runs on September 27, 2026, Claude Fable 5.1 passed 3 of 5 of our writing prompts (neither hard one): tied 16th of 20 models. Each reply counted as 1 message on Pro, where it has 31 a month, and cost $0.0172 to run on average.
Prompt by prompt
Each of the 5 writing prompts, and how Claude Fable 5.1's reply did.
| Prompt | Result | Cost | Time |
|---|---|---|---|
| Announce a second bakery shop on LinkedInEveryday | Passed: Graded 4.8 of 5 on average (lowest 4). | $0.0184 | 7.3 s |
| Rewrite corporate jargon in plain wordsEveryday | Passed: Graded 4.3 of 5 on average (lowest 4). | $0.0130 | 6.0 s |
| Decline a meeting and offer two timesEveryday | Passed: Graded 5.0 of 5 on average (lowest 5). | $0.0145 | 4.7 s |
| A product announcement with five rulesHard | Failed: Graded 3.7 of 5 on average (lowest 3). | $0.0157 | 5.9 s |
| Argue both sides of free busesHard | Failed: Graded 4.7 of 5 on average (lowest 4); but a paragraph of 99 words, over the 90 allowed. | $0.0246 | 9.3 s |
Every writing reply from Claude Fable 5.1
Announce a second bakery shop on LinkedIn
An everyday prompt: “Announce a second bakery shop on LinkedIn”, in full.
Passed: Graded 4.8 of 5 on average (lowest 4).
We're opening a second Crumb & Co. When we started baking out of one small shop, we didn't imagine we'd ever need a second oven, let alone a second door. But our customers kept coming back, kept telling their friends, and kept asking whether we might ever open somewhere closer to them. So we listened. On 14 November, Crumb & Co. opens in Leeds. It'll be the same bread, the same pastries, and the same early mornings, just in a new neighbourhood. We've been baking test batches for weeks to make sure the first loaf out of the Leeds oven tastes exactly like the ones you already know. To say thank you, coffee is on us all day on opening day. Come by, have a cup, and try something warm from the counter. We'd love to see you there. Thank you for getting us here.
540 tokens in, 259 out · 7.3 s · $0.0184 · 1 message on Pro · answered by anthropic/claude-fable-5.1 via Anthropic ·
Rewrite corporate jargon in plain words
An everyday prompt: “Rewrite corporate jargon in plain words”, in full.
Passed: Graded 4.3 of 5 on average (lowest 4).
In Q3, teams from different departments worked together on a project to put customers first. Among enterprise (large business) customers, this raised the retention rate by 12% and slowed the rate at which customers left by 0.3 percentage points. The company also cut back on some of the ways it communicates with customers—across channels like phone, email, and in-app—to free up staff time.
599 tokens in, 114 out · 6.0 s · $0.0130 · 1 message on Pro · answered by anthropic/claude-fable-5.1 via Anthropic ·
Decline a meeting and offer two times
An everyday prompt: “Decline a meeting and offer two times”, in full.
Passed: Graded 5.0 of 5 on average (lowest 5).
Subject: Wednesday Vendor Demo Hi Tom, Thanks for the invitation to the vendor demo on Wednesday at 11:00. Unfortunately, I'm presenting to the board at that time and won't be able to attend. Would Thursday at 10:00 or Friday at 14:00 work instead? I'd still very much like to see the demo, so I'm happy to go with whichever suits you and the vendor better. Apologies for the inconvenience, and thanks for your flexibility. Best regards, [Your Name]
544 tokens in, 182 out · 4.7 s · $0.0145 · 1 message on Pro · answered by anthropic/claude-fable-5.1 via Anthropic ·
A product announcement with five rules
A hard prompt: “A product announcement with five rules”, in full.
Failed: Graded 3.7 of 5 on average (lowest 3).
**Introducing the Nordvik 2** The Nordvik 2 desk lamp brings quiet precision to your workspace. Five dimming steps let you move from focused task lighting to a soft evening glow with a single touch. The arm rotates a full 270 degrees, so light lands exactly where you need it, whether you are reading, sketching or working at a screen. Power comes through USB-C, the same cable you already use for your phone and laptop, keeping your desk uncluttered. The Nordvik 2 is priced at €79 and ships on 1 December. Is your desk ready for light that finally adapts to you?
556 tokens in, 203 out · 5.9 s · $0.0157 · 1 message on Pro · answered by anthropic/claude-fable-5.1 via Anthropic ·
Argue both sides of free buses
A hard prompt: “Argue both sides of free buses”, in full.
Failed: Graded 4.7 of 5 on average (lowest 4); but a paragraph of 99 words, over the 90 allowed.
Free buses remove the single biggest barrier to ridership: the fare. Every boarding becomes faster with no payment friction, cutting dwell times and making service more reliable. Low-income residents, who spend a disproportionate share of income on transport, gain immediate relief, expanding access to jobs, schools, and healthcare. More riders mean fewer cars, less congestion, and cleaner air for everyone. Fare collection itself costs money—equipment, enforcement, cash handling—that could be redirected to service. Cities like Kansas City and Tallinn show ridership rises and communities benefit. Fares typically cover a meaningful slice of operating costs, and abolishing them creates a permanent hole that must be filled by taxes or, more often, by cutting service. Riders consistently say they want frequency and reliability more than free trips; a bus that comes every eight minutes is worth more than one that's free but comes every thirty. Free systems in practice draw riders from walking and cycling, not from cars, so climate gains are marginal. Overcrowding, vandalism, and buses used as shelters have strained free networks. Targeted discounts for those in need deliver equity without sacrificing service quality.
520 tokens in, 388 out · 9.3 s · $0.0246 · 1 message on Pro · answered by anthropic/claude-fable-5.1 via Anthropic ·
How it compares on writing
Claude Fable 5.1 beside the job's picks among every model. 3 models share the hard-problems pick, and Claude Fable 5.1 isn't one of them.
| Model | Passed | On Pro | Cost per reply |
|---|---|---|---|
| DeepSeek V4 ProOur pick: hard problems (shared), best value | 5 of 5 | 250 a month on Pro | $0.0011 |
| GPT-6 LunaOur pick: hard problems (shared), everyday | 5 of 5 | 60 a day on Pro | $0.0001 |
| Claude Fable 5.1 | 3 of 5 | 31 a month on Pro | $0.0172 |
Every limit is published. Paid plans also have a monthly fair-use limit on AI cost: Plus $3.75, Pro $7.50, Max $20, Ultra $42, Studio $85. Using every message on your plan at typical sizes stays under it; very large messages and heavy research use it faster. Every limit, explained.
Claude Fable 5.1 next to each model on writing
Claude Fable 5.1 against each model on the same 5 writing prompts. One run each, through OpenRouter: a wait depends on the provider and the load that day, so a lead under 10% counts as close.
Against Claude Opus 5.5: Claude Fable 5.1 answered 1.4× sooner (6.0 s to 8.2 s), cost within 10% of it, and passed 3 of 5 to its 4. Only Claude Opus 5.5 passed A product announcement with five rules.
Against Claude Sonnet 5.5: Claude Fable 5.1 answered 2.5× later (6.0 s to 2.3 s), cost 5.1× more, and passed 3 of 5 to its 4. Only Claude Sonnet 5.5 passed A product announcement with five rules.
Against Claude Sonnet 5: Claude Fable 5.1 answered 1.3× later (6.0 s to 4.5 s), cost 5.1× more, and passed 3 of 5 to its 4. Only Claude Fable 5.1 passed Announce a second bakery shop on LinkedIn. Only Claude Sonnet 5 passed A product announcement with five rules; Argue both sides of free buses.
Against Claude Haiku 5.5: Claude Fable 5.1 answered 3.9× later (6.0 s to 1.5 s), cost 107.2× more, and passed 3 of 5 to its 3. Only Claude Fable 5.1 passed Rewrite corporate jargon in plain words. Only Claude Haiku 5.5 passed A product announcement with five rules.
Against Claude Haiku 4.5: Claude Fable 5.1 answered 2.7× later (6.0 s to 2.2 s), cost 15.2× more, and passed 3 of 5 to its 4. Only Claude Haiku 4.5 passed Argue both sides of free buses.
Against GPT-6 Astra: Claude Fable 5.1 answered 1.2× later (6.0 s to 4.8 s), cost 1.6× more, and passed 3 of 5 to its 5. Only GPT-6 Astra passed A product announcement with five rules; Argue both sides of free buses.
Against GPT-6.1 Sol: Claude Fable 5.1 answered 1.8× later (6.0 s to 3.3 s), cost 15.2× more, and passed 3 of 5 to its 4. Only Claude Fable 5.1 passed Rewrite corporate jargon in plain words. Only GPT-6.1 Sol passed A product announcement with five rules; Argue both sides of free buses.
Against GPT-6 Sol: Claude Fable 5.1 answered 1.7× later (6.0 s to 3.5 s), cost 7.6× more, and passed 3 of 5 to its 4. Only Claude Fable 5.1 passed Rewrite corporate jargon in plain words. Only GPT-6 Sol passed A product announcement with five rules; Argue both sides of free buses.
Against GPT-6 Luna: Claude Fable 5.1 answered 2.5× later (6.0 s to 2.4 s), cost 173.5× more, and passed 3 of 5 to its 5. Only GPT-6 Luna passed A product announcement with five rules; Argue both sides of free buses.
Against Gemini 4 Argon: Claude Fable 5.1 answered within 10% of its time (6.0 s to 5.7 s), cost 12.3× more, and passed 3 of 5 to its 4. Only Gemini 4 Argon passed A product announcement with five rules.
Against Gemini 3.1 Pro (preview): Claude Fable 5.1 answered 1.5× sooner (6.0 s to 9.1 s), cost 1.9× more, and passed 3 of 5 to its 4. Only Gemini 3.1 Pro (preview) passed A product announcement with five rules.
Against Gemini 3.8 Flash: Claude Fable 5.1 answered 1.5× later (6.0 s to 3.9 s), cost 13.1× more, and passed 3 of 5 to its 3. Only Claude Fable 5.1 passed Rewrite corporate jargon in plain words. Only Gemini 3.8 Flash passed Argue both sides of free buses.
Against DeepSeek V4.1 Flash: Claude Fable 5.1 answered 4.5× later (6.0 s to 1.3 s), cost 38.3× more, and passed 3 of 5 to its 4. Only Claude Fable 5.1 passed Rewrite corporate jargon in plain words. Only DeepSeek V4.1 Flash passed A product announcement with five rules; Argue both sides of free buses.
Against DeepSeek V4 Pro: Claude Fable 5.1 answered 1.5× later (6.0 s to 3.9 s), cost 16.1× more, and passed 3 of 5 to its 5. Only DeepSeek V4 Pro passed A product announcement with five rules; Argue both sides of free buses.
Against Grok 4.7: Claude Fable 5.1 answered within 10% of its time (6.0 s to 6.0 s), cost 3.0× more, and passed 3 of 5 to its 3. Only Claude Fable 5.1 passed Rewrite corporate jargon in plain words. Only Grok 4.7 passed A product announcement with five rules.
Against Kimi K3: Claude Fable 5.1 answered 2.0× later (6.0 s to 3.0 s), cost 4.5× more, and passed 3 of 5 to its 4. Only Kimi K3 passed Argue both sides of free buses.
Against GLM 5.3: Claude Fable 5.1 answered 3.4× later (6.0 s to 1.8 s), cost 30.0× more, and passed 3 of 5 to its 4. Only GLM 5.3 passed A product announcement with five rules.
Against GLM 5.3 Flash: Claude Fable 5.1 answered 1.4× sooner (6.0 s to 8.5 s), cost 53.9× more, and passed 3 of 5 to its 2. Only Claude Fable 5.1 passed Rewrite corporate jargon in plain words.
Against Mistral Large 4: Claude Fable 5.1 answered 1.6× sooner (6.0 s to 9.8 s), cost 7.2× more, and passed 3 of 5 to its 4. Only Mistral Large 4 passed Argue both sides of free buses.
How these runs were done
Rubric (graded). The grader model scores the reply from 1 to 5 on each published criterion. It passes with an average of 4 or more and no criterion under 3, and only if it also meets the prompt's automatic rules (length, words it must or mustn't use).
The grader is Claude Opus 5.5 at low reasoning effort; its own replies are graded by GPT-6 Astra, so no model grades itself. Its prompt and every rubric are on the methods page.
Claude Fable 5.1, and writing, elsewhere
- Claude Fable 5.1: price, limits and messages on every plan
- The best AI for writing: our picks among every model
- Claude for writing
- Claude Fable 5.1 for coding: our test runs
- Claude Fable 5.1 for math: our test runs
- Claude Fable 5.1 for data analysis: our test runs
- Claude Fable 5.1 vs GPT-6 Astra
- Claude Fable 5.1 vs Claude Opus 5.5
- Claude Fable 5.1 vs Kimi K3
- Claude Fable 5.1 vs Grok 4.7
- Claude Fable 5.1 vs Claude Sonnet 5
- Claude Fable 5.1 vs Claude Haiku 4.5
- Rewrite for clarity: the prompt, and its price on each model
- AI prompts for writing, tested on four models
- Essay prompts for AI that help you write your own
- Our test runs: 50 prompts on every model
Questions
Is Claude Fable 5.1 good for writing?
In our test runs it passed 3 of 5 writing prompts, tied 16th of the 20 models in llmwise. Every reply is on this page, so you can judge them yourself.
How many of my messages does a writing reply from Claude Fable 5.1 use?
1 message each on Pro, where it has 31 a month on Pro. The price of a message is fixed and shown before you send it, however long the reply.
How were these runs done?
The same way for every model: each prompt sent through llmwise's own pipeline, each reply checked the same way. The methods page has every prompt and how each is scored.
Claude, GPT, Gemini, DeepSeek, Grok, Kimi, GLM, and Mistral, in one chat.
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