Model Scorecard
Claude Opus 4.8 (max effort)
Anthropic · proprietary
Claude Opus 4.8 ranks #19 of 87 models on the November 2026 ToneBench board, and Claude Opus 4.8 (max effort) is its best configuration, #39 of 151 configurations, with a Writing Score of 80.7/100 and a Writing Elo of 1926. One script costs $1.23 at API list price.
Last updated , from board data generated at 17:52 UTC.
Rank, scores, the nine metrics, the 10 reference scripts, cost and setup for one configuration (a model at one reasoning setting). Key Results sums it up; the section links below it jump to the detail.
Key Results
- StandingClaude Opus 4.8 ranks #19 of 87 models, and this is its best configuration. As a configuration, it is #39 of 151 configurations by Writing Elo (1926), in the upper third of the board. Its 95% range (1889 to 1958) overlaps 22 other configurations, ranked #32 to #55.
- MetricsBest-ranked: Length Adherence (94.6, 25th of 151 configurations, +9.8 against the board median). Lowest-ranked: Substance, Accuracy & Value (82.0, 74th of 151 configurations, +0.2 against the board median).
- ScriptsFrom 77.5 on Script 4 (short explainer) to 83.1 on Script 6 (founder announcement): a 5.6-point spread across the 10 reference scripts.
- ConsistencyIts Writing Score moves ± 2.0 between drafts of the same script, against ± 2.5 for the median configuration: typical.
- ValueDeepSeek V4.1 Flash 1017 (high) ranks higher with an overlapping Elo range and costs about $0.0095 per script, against $1.23 per script for this one.
Louis's PickOf the two Claude Opus 4.8 settings, this is the one I'd use. If you're not tied to Claude Opus 4.8, Claude Opus 5.5 (xhigh) ranks clearly higher for no more per script.
More Context Behind These Results
Writing Elo comes from comparing its average on each script with every other configuration's average on that same script; a gap smaller than the draft-to-draft variation counts as a draw (what the ranges can and cannot show).
On Length Adherence, its best-ranked metric, its drafts land near the target length, so they need less trimming or padding. Even its lowest-ranked metric, Substance, Accuracy & Value, ranks in the top half of the board, so no metric stands out as a weak spot.
The script format moves its score. If most of your scripts look like its best or weakest format, that result is a better guide than the average.
Among proprietary models, Claude Opus 4.8 is 14th of 53. As a configuration, it is 33rd of 108 proprietary configurations. The best open-weight configuration, GLM-5.3 (max) at configuration #22, outranks it.
All Settings of Claude Opus 4.8
Claude Opus 4.8 is also on the board at other effort settings, and none of them rank above this one. The thinking-level page for Claude Opus 4.8 charts how quality, cost and time change with the setting.
| Setting | Configuration Rank | Writing Score | Writing Elo | Cost / Script | Time / Script |
|---|---|---|---|---|---|
| max effort this page | #39 | 80.7 | 1926 | $1.23 | 9.8 min |
| high | #59 | 79.3 | 1789 | $0.193 | 1.4 min |
Skill Profile Across the Nine Metrics
Each corner is one metric on a 0 to 100 scale; the further out, the higher the score. A corner outside the dashed line beats the board median. Hover or tap a point for its exact score, and a metric name for what it rewards.
Scores by Metric
Nine metrics, each scored 0 to 100 and weighted into the Writing Score; the weight sits under each name. Rank is out of all 151 ranked configurations.
Scores by Reference Script
Every ranked configuration writes five drafts for each of the same 10 briefs, and each score is the mean of those drafts. The rank and board median compare it with every configuration on that script, which separates a weak result from a hard script. The result on the format closest to your own work is the most relevant.
Consistency Between Drafts
Every score on this page is the mean of 5 drafts per script. The ± is the standard deviation between those drafts: the larger it is, the more two drafts of the same script can differ.
Compared with the typical model, it's steadiest on Length Adherence: ± 3.9 between drafts against ± 6.6.
Consistency by Metric
| Metric | This model | Board median | Verdict |
|---|---|---|---|
| Tone & Voice Match ? | 76.7 ± 1.5 | ± 1.9 | typical |
| Writing Craft & Clarity ? | 76.7 ± 1.4 | ± 1.5 | typical |
| Substance, Accuracy & Value ? | 82.0 ± 2.0 | ± 2.1 | typical |
| Continuity & Emotion ? | 80.9 ± 1.3 | ± 1.5 | typical |
| YouTube Best Practices ? | 80.4 ± 2.4 | ± 2.4 | typical |
| Hook Strength ? | 80.3 ± 3.2 | ± 2.7 | typical |
| Length Adherence ? | 94.6 ± 3.9 | ± 6.6 | steadier than most |
| Slop Score ? | 82.1 ± 1.4 | ± 1.6 | typical |
| Visual Cue Quality ? | 79.7 ± 2.3 | ± 2.9 | typical |
Cost, Time and Tokens per Script
Logged on every run; none of these figures affects the Writing Score. Time is the average time to one accepted script, retries included. Cost is one script at the API list price.
Scores by Judge
Four judges score the same 50 stored drafts blind against the same rubric: three LLM judges from three labs, plus Jev, a typed judge from TypeSafe that rates each metric on five described quality levels. No single judge's taste decides the result. The Writing Score of 80.7 combines their scores with the parts computed in code (Length Adherence and half of the Slop Score). The highest and lowest judge are 12.5 points apart on its Writing Score. That is close to the board median of 13.4. Each judge also has its own scale, so every card shows that judge's score against its average across the board. How the panel works.
Evaluation Setup
How this exact configuration was run and judged: route, model ID, dates, sampling and prompt.
- Accessed viaClaude Code (Anthropic subscription).
- Exact model / route id
claude-opus-4-8atreasoning level: max. - Generations5 independent runs × 10 scripts = 50 drafts, stored after generation and never edited.
- Run dates2026-10-08.
- JudgesClaude 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 from TypeSafe. One call per judge per draft. All four score every draft on their own, blind to which model wrote it. The three LLM judges use the identical rubric and have to quote evidence before they score a metric. Jev answers the same rubric as one question per metric, choosing among five described quality levels, and writes no text. Seven metrics are the plain average of the four judges. Length is computed from the spoken word count, and Slop is half computed (lexical scans minus the spoken-dash penalty) and half judged. The Writing Elo is cross-checked with a Bradley-Terry fit of the same pairwise results (methodology).
- Sampling and promptThe provider's default sampling, with no fine-tuning and no system-prompt changes. Every current-ranked model gets the same prompt, about 13,000 tokens (the count shifts a bit with each model's tokenizer): a style guide built from Louis's voice and storytelling guides, the target length, and the brief with its research packet. Generation is closed-book on every route: the prompt is the only source, with no web search, browsing, code execution, file access or other tool (generation).
- What stays privateThe exact rubric and any non-public reference material. Each script is normally benchmarked before its video is published, which lowers the odds that a model has seen the reference, though it does not rule it out (why).
Frequently Asked Questions
How Good Is Claude Opus 4.8 (max effort) at Writing?
Claude Opus 4.8 ranks #19 of 87 models on ToneBench, and this is its best configuration. This configuration is #39 of 151 configurations, in the upper third of the board, with a Writing Elo of 1926 and a Writing Score of 80.7/100. The ranks come from full YouTube scripts written in the voice of Louis-François Bouchard and judged blind, with the channel's finished script as the reference. The benchmark measures long-form scripted writing, so the result does not carry over to every kind of text.
Is Claude Opus 4.8 (max effort) the Best Anthropic Model for Writing?
No. Claude Opus 4.8 is 7th of 13 Anthropic models. The top one is Claude Opus 5.5, through Claude Opus 5.5 (xhigh), about 778 Elo ahead of this setting.
Is Claude Opus 4.8 (max effort) Good Value for the Money?
It costs about $1.23 per script. DeepSeek V4.1 Flash 1017 (high) ranks higher with an overlapping Elo range and costs less.
What Are the Strengths and Weaknesses of Claude Opus 4.8 (max effort)?
Its best-ranked metric is Length Adherence (94.6, 25th of 151 configurations, +9.8 against the board median), and its lowest-ranked is Substance, Accuracy & Value (82.0, 74th of 151, +0.2). Even that one ranks in the top half of the board. The Scores by Metric section shows the board median and the board's best for each one.
How Was Claude Opus 4.8 (max effort) Evaluated?
It was run through Claude Code (Anthropic subscription), with the exact model/route ID claude-opus-4-8 at reasoning effort max, first run on 2026-10-08. It wrote each script 5 times with the provider's default sampling and no fine-tuning. The Evaluation Setup section and the methodology page have the details.
Does Claude Opus 4.8 (max effort) Have Open Weights?
No. It is a proprietary model: its weights are not public. Among proprietary configurations it is 33rd of 108 for writing.