Towards AITowards AIToneBench

Model Comparison

Claude Fable 5.1 vs Kimi K3.1 Pro

Claude Fable 5.1 (max effort) leads Kimi K3.1 Pro (max) by 327 Elo, and their 95% ranges sit 243 Elo apart. Even Claude Fable 5.1's lowest-rated configuration, Claude Fable 5.1 (high), ranks above Kimi K3.1 Pro (max). Among 83 models, each ranked by its best configuration, Claude Fable 5.1 is #3 and Kimi K3.1 Pro is #7. Cost per script: $3.56 for Claude Fable 5.1 (max effort) and $0.251 for Kimi K3.1 Pro (max).

Last updated , from board data generated at 22:06 UTC.

Claude Fable 5.1
2532 Writing Elo of Claude Fable 5.1 (max effort), its best configuration#3 of 83 models · 84.5/100 Writing Score · $3.56 per script2 configurations on the board
Kimi K3.1 Pro
2205 Writing Elo of Kimi K3.1 Pro (max), its best configuration#7 of 83 models · 82.5/100 Writing Score · $0.251 per script1 configuration on the board

Picks and Verdict

PickClaude Fable 5.1

Claude Fable 5.1 (max effort)

Pick Claude Fable 5.1 (max effort) for the script you film, since it leads Kimi K3.1 Pro (max) by 327 Elo with separate ranges and wins every script, at $3.56.

PickKimi K3.1 Pro

Kimi K3.1 Pro (max)

Pick Kimi K3.1 Pro (max) for research-heavy drafts at $0.251 a script, about a seventh of what Fable charges at high, with slightly stronger substance and visual cues.

Claude Fable 5.1 is the better writer here at both of its settings, and the gap is wide. Ranked by best configuration, it's the #3 model of 83 against Kimi K3.1 Pro, the #7 model. Claude Fable 5.1 (max effort) leads Kimi K3.1 Pro (max) by 327 Elo with separate 95% ranges and wins all ten scripts. Even Claude Fable 5.1 (high) sits 120 Elo above Kimi with ranges apart. Kimi only runs at max on this board, since the model always reasons and max is Moonshot's default, so there's no cheaper Kimi setting to fall back on. Price is where Kimi fights back: $0.251 and 5.5 minutes a script, against $1.85 for Fable at high and $3.56 and over twelve minutes at max effort. Fable's max effort earns that price, with 207 Elo over high for about 1.9 times the cost and steadier drafts. Fable pulls ahead on voice, almost five points up on tone and four on YouTube structure. Kimi's substance, visual cues and hooks are a little stronger. For the script I film, I'd pay for Fable at max effort. For research-heavy first drafts, Kimi is a lot of model for a quarter.

Disclosure: Claude Fable 5.1 comes from the same lab as one of the four judges, Claude Opus 5.5. The other three sit outside its lab, so it is never scored by its own lab alone (how the panel works). The judge analysis measures how much each judge favors its own lab.

How to Read the Writing Score, Writing Elo and 95% Ranges

Writing Score and Writing Elo. The Writing Score (0 to 100) is the weighted average of the nine metric scores: seven from the judges, Length Adherence from code and the Slop Score half from each. The Writing Elo is a rating from pairwise comparisons: on each script, each configuration's average across its drafts is compared with every other configuration's, and gaps within the draft-to-draft variation count as draws. Elo rewards winning often, so the two can put configurations in a different order.

Elo ranges. Each 95% range shows how far a configuration's Elo could move if the drafts had come out slightly differently. It comes from resampling every configuration's recorded draft scores on each reference script and ranking again. Comparing two separate ranges does not test the Elo gap between them: ranges far apart are strong evidence for the order, and overlapping ranges do not mean a tie. The reference scripts stay fixed, so the ranges say nothing about new scripts. The methodology page has the full description.

All Thinking Levels of Both Models

Every ranked configuration of Claude Fable 5.1 and Kimi K3.1 Pro, scored on the same 10 scripts by the same four judges.

How to Read the Chart
  • Each row is one configuration: the model at one thinking level. The dot is its Writing Elo, a rating from pairwise comparisons of the scores on each script, and the bar is its 95% range: how far that Elo could move if the drafts had come out slightly differently.
  • When two bars overlap, the board cannot order those two configurations. Bars far apart are strong evidence for the order.
  • The table under the chart lists the same configurations in the same order and adds the Writing Score (the 0 to 100 consensus of the judges and code), cost, time and configuration rank (the place among all configurations on the board).
Claude Fable 5.1Kimi K3.1 Pro
ConfigurationWriting Elo95% RangeWriting ScoreCost / ScriptTime / ScriptReasoning TokensConfiguration Rank
Claude Fable 5.1 (max effort)25322489 to 256984.5$3.5612.3 minN/A#4
Claude Fable 5.1 (high)23252269 to 238083.4$1.856.3 minN/A#9
Kimi K3.1 Pro (max)22052166 to 224682.5$0.2515.5 min19,487#14

Cost is one script at the API list price of the route used, uncached and without judging. Time is the average for one accepted script, retries included. N/A under Reasoning Tokens means the board has no separate reasoning count for that route.

Computed Findings Across Thinking Levels

Each finding is computed from the configurations above. Where two 95% ranges overlap, the board cannot order those two configurations.

Two Chosen Configurations Compared

Pick one configuration of each model to compare their metric scores, consistency across drafts and per-script scores. Each menu starts on the model's best configuration.

Scores by Metric

Claude Fable 5.1 (max effort)Kimi K3.1 Pro (max)Solid bar: higher score in that row

Claude Fable 5.1 (max effort) scores higher on six of the nine metrics and Kimi K3.1 Pro (max) on three. Weighted by each metric's share of the Writing Score, Tone & Voice Match does the most to put Claude Fable 5.1 (max effort) ahead, with a 4.8-point lead on that metric. The weight beside each metric is its share of the Writing Score.

Tone & Voice Match19% weight
81.8
77.0
Writing Craft & Clarity13% weight
80.8
77.8
Substance, Accuracy & Value15% weight
86.0
88.2
Continuity & Emotion14% weight
84.5
80.8
YouTube Best Practices12% weight
83.7
79.7
Hook Strength10% weight
82.0
83.4
Length Adherence8% weight
98.3
95.4
Slop Score5% weight
86.8
85.0
Visual Cue Quality4% weight
82.7
84.9

Consistency Across Drafts

Claude Fable 5.1 (max effort)Kimi K3.1 Pro (max)
Score spread across drafts (±)1.131.65
Lowest script score82.8 Script 1080.4 Script 7
Highest script score86.2 Script 985.5 Script 9
Range across scripts3.45.1

Spread is how much the Writing Score moves between a configuration's drafts, and lower is steadier. Green marks the better number in each row.

Scores by Script

Writing Score on each reference script. Gap is Claude Fable 5.1 (max effort) minus Kimi K3.1 Pro (max), and the higher score is in bold.

ScriptClaude Fable 5.1 (max effort)Kimi K3.1 Pro (max)Gap
Script 1 opinion / warning explainer83.381.3+2.0
Script 2 news-analysis / skeptical explainer83.883.2+0.6
Script 3 personal roadmap / opinion84.081.9+2.1
Script 4 short explainer85.282.0+3.2
Script 5 news-analysis / opinion explainer84.984.2+0.7
Script 6 founder announcement / personal origin story85.083.0+2.0
Script 7 personal technical walkthrough / agentic workflow case study85.380.4+4.9
Script 8 product release announcement / personal observation84.782.1+2.6
Script 9 career guide / hiring analysis86.285.5+0.7
Script 10 engineering process walkthrough / presentation adaptation82.881.3+1.5

Compare With Another Model

Pick a second model. A pair with its own written match-up opens that page, and any other pair opens in the comparison tool.

Nearby Match-Ups by Best Writing Elo

Every configuration wrote five drafts for each of the same 10 briefs, from the same prompt. Generation was closed-book, with the prompt as the only source and no web search or other tools. Each judge scores every draft once: Claude Opus 5.5 at medium effort through the Claude Code subscription, GPT-6.1 Sol at medium reasoning through the Codex CLI, GLM 5.3 Flash through OpenRouter, and Jev 1.13, a typed judge from TypeSafe that answers each metric as a multiple-choice question. The channel's finished script is their reference for the voice, and it gets no score on the board itself.

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