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🔍 Read the full analysis: How I Use Three AI Tools In September 2026 on ThorstenMeyerAI.com

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TL;DR

Thorsten Meyer says he uses Claude Opus 5.5 for building, GPT-6.1 Sol for detailed work and review, and Jev for high-volume yes-or-no and routing decisions. His account draws on Artificial Analysis Intelligence Index v4.3.x, which places several models near one another in score while showing large differences in reported cost per task. These are his workflow choices, not proof that the same models will suit other workloads.

On September 29, 2026, Thorsten Meyer described using Claude Opus 5.5 to build, GPT-6.1 Sol to examine details and review work, and Jev for high-volume yes-or-no and routing decisions. His account argues that reported task costs can differ sharply among models with relatively close benchmark scores, a distinction that could affect how teams assign routine and demanding work.

Meyer says Opus 5.5 at high or xhigh effort is his main model for features, APIs, multi-file work and refactoring. He reserves xhigh for difficult tasks such as architecture, migrations and trust boundaries. In the Artificial Analysis Intelligence Index v4.3.x figures he cites, Opus scores 54 at high for $1.82 per task and 56 at xhigh for $3.46. Its max setting scores 58 but costs $5.98 per task.

He assigns GPT-6.1 Sol detailed file and code-diff work, along with review of Opus’s output. The index figures he quotes list Sol at medium for $0.21 per task, high for $0.32 and xhigh for $0.39. At high and xhigh, the reported time to first token is 57 and 69 seconds, respectively, which Meyer says makes those settings less suited to interactive use. He calls a separate model family a useful second pair of eyes, while warning that different models can still share a flawed specification.

For other work, Meyer names Jev as a decision model for routing and binary judgments, and lists Astra, Fable, Sonnet and Luna as alternatives for selected jobs. He says Sonnet’s high setting suits scoped work and documents, while Luna suits classification and extraction. His proposed practice is to test models against the intended workload before switching; the source does not provide those shadow-test results.

At a glance
reportWhen: Published September 29, 2026; GPT-6.1 S…
The developmentThorsten Meyer published a September 29 account of how he assigns building, review and routing work across three AI tools, citing model scores and costs.

Opus builds. Sol reviews. Jev decides.

The September 2026 AI stack in one page: six frontier models on one price curve, and a decision model for the high-volume judgements that do not need a sentence.
Scores: Artificial Analysis Intelligence Index v4.3.x. Data as of 29 September 2026.
BuildsClaude Opus 5.5 at high or xhigh effort
Digs and reviewsGPT-6.1 Sol at high or xhigh effort
DecidesJev on high-volume yes/no and routing calls

One price tape, six models

Put every model on the same cost-per-task ruler and capability looks compressed. The bill does not.
Price tape: cost per task of six models on a log scale, from GPT-6 Luna at $0.07 to Fable 5.1 at $7.63$0.05$0.10$0.50$1$5$10cost per task, log scale: each tick is a different order of magnitudeGPT-6 Lunaindex 37 · $0.07GPT-6.1 Solindex 51 · $0.39 (xhigh)GPT-6 Astraindex 53 · $3.26Opus 5.5index 58 · $5.98Sonnet 5.5 · index 56 · $7.60Fable 5.1 · index 53 · $7.63about 100× from the cheapest to the priciest, but only 21 index points between them

Score against cost, at every effort setting

Each dot is an effort level. Opus 5.5 at high already matches Astra and Fable at max on this index, for less money.
Intelligence Index score against cost per task for each effort setting of six models$0.01$0.10$1$102030405060cost per Intelligence Index task, log scaleindexOpus high / xhigh: my defaultOpus 5.5Sonnet 5.5Fable 5.1GPT-6 AstraGPT-6.1 Sol (new)GPT-6 Sol (Sep 22), dashedGPT-6 Lunaup and to the left is better
Astra and Fable are shown at their top published setting. Luna starts at $0.0045 per task. GPT-6.1 Sol has no low or max setting published yet.

The effort dial moves the bill more than the model

Going from medium to max on Opus costs 4.46× more for 7 points. That is why I run high or xhigh.

Claude Opus 5.5

$0.55
42
$1.34
51
$1.82
54
$3.46
56
$5.98
58
low
medium
high
xhigh
max
Solid bars are where I run it. Max adds 2 points over xhigh for 73% more cost.

Claude Sonnet 5.5

$0.41
36
$0.59
41
$1.08
47
$2.74
52
$7.60
56
low
medium
high
xhigh
max
Best value is high. At max it writes about 193k output tokens per task, the most measured.

GPT-6.1 Sol: near-Astra scores at a fraction of the price

Launched 29 September at $2 in and $10 out per 1M tokens. It sits 1 to 2 points under Astra and Fable, and Opus xhigh still leads it by 5.

Three published settings

SettingIndexCost per taskOutput tokensFirst token
medium48$0.2115M5.3 s
high50$0.3225M57 s
xhigh51$0.3936M69 s
Median for comparable models is 82M output tokens. High and xhigh are not interactive: plan for a wait before the first token.

Same score band, very different bill

GPT-6.1 Sol xhigh
$0.39index 51
Opus 5.5 high
$1.82index 54
GPT-6 Astra max
$3.26index 53
Opus 5.5 xhigh
$3.46index 56
Fable 5.1 max
$7.63index 53
Cost per Intelligence Index task. A one-point gap is inside the noise.

My stack: who builds, who reviews

Opus does the work. A second model family reviews it, because a different reviewer catches what the author cannot see.
Stack diagram: Opus 5.5 builds at high effort, escalates to xhigh, and sends every change to GPT-6.1 Sol for review; Astra or Fable give a second opinionOpus 5.5 · xhighhard problems: architecture,migrations, trust boundariesOpus 5.5 · highMAIN BUILDERfeatures, APIs, multi-filework, refactorsescalate when it gets hardGPT-6.1 Solhigh or xhighdigs into details andreviews every change$0.32–0.39 per taskdifffindingsAstra or Fablesecond opinion, 8 to 20×the cost per taskif they disagreeSonnet 5.5 · Lunaside work: scopedsubtasks, bulk checksand routingFailed review? Hand Opus the failing case and the evidence.Never just “try harder”: effort cannot supply a missing requirement.
Effort is not capability. Turning the dial up does not make a model smarter.
Effort cannot fill gaps. A missing requirement stays missing at any setting.
Different model, same spec. That is not independent review if both read the same flawed brief.
Green tests are not approval. Passing tests only prove what the tests cover.

Cheaper tokens are not cheaper work

Illustrative, not measured: $1 of model time plus 4 minutes of review at $45 an hour. Halving the model price saves 12.5% of the total. One extra minute of review erases it.
$4.00
review $3.00
model $1.00
Baseline
$3.50
review $3.00
model $0.50
Model price cut 50%
$4.25
review $3.75
model $0.50
Cheaper model plus 1 extra minute of review
Track cost per accepted result: model, tools, review and rework, divided by the results someone actually uses.

Read the numbers with four warnings

The index movesFable scored 66 on an earlier version and 53 on v4.3. Compare within one version only.
Fallback is includedFlagged cyber and biology tasks route to older Anthropic models, now on Sonnet 5.5 too.
Max is not productionReal deployments run medium or high, where gaps narrow and costs fall.
Your work decidesShadow-test on your own tasks. Budget cost per task, not per token.

Part 2: Jev, the model that decides instead of writing

Jev cannot write, summarise or extract. It answers narrow typed questions with a probability and an honest confidence, in under a second, for about $0.04 per million input tokens.

One call in, typed answers out

Your code, not Jev, decides what to do with each answer, usually by confidence band.
Jev flow: state and typed questions go into one Jev call; typed answers with confidence come out; code acts alone, escalates the gray zone, or logsStatea ticket, a story,a site profile,a log line …+ typed questions,many per callJevone call0.3 to 0.9 s$0.042 / M tokens inAnswersnoul: 0.03choice: billing p 0.91, conf 0.86score: 2.7 of 3 conf 0.64code branches on thisAct aloneconf ≥ 0.8Escalategray zone toLLM or humanLogmeasure first

Three question types

noul
A yes/no question. Returns the probability of yes, 0 to 1.
gates, flags, filters
choice
Pick one option. Returns the choice, a probability per option, and a confidence.
routing, classification, taxonomy
score
Rate on your ordered levels. Returns a position (it can fall between levels) plus a confidence.
quality, fit, severity, priority

Confidence is the superpower

In my own measurement on a 31-topic classification, Jev agreed with a frontier LLM almost every time it was sure, and rarely when it was not. So: decide the clear cases, route the gray zone.
confidence 0.8 or higher
97–99%
all answers
89%
confidence below 0.5
42%
Agreement with a frontier LLM, my production data, September 2026, rounded.

Three uses running in my publishing operation

About 90,000 decisions so far. Checks I could only afford on a sample now cover everything.
$2.01
Language check
78,889 articles scanned overnight. 1,576 in the wrong language found, 1,553 fixed in place.
22%
Relevance gate
About 10,000 story-to-site pairings judged in 3 days. Only 22% were clearly on-topic.
89%
Classifier fallback
Agreement with the primary LLM across 31 topics, used when that LLM errors.

The fit test, then the shadow test

Use Jev only when all four hold. Then prove it on past decisions before it acts on anything.
High volumeThousands of small calls, not a handful of big ones.
Narrow questionNo multi-step reasoning needed.
Cheap errorsOr unsure cases go to something smarter.
Heuristic failsVisibly, and measured, not assumed.
  1. Replay 300 to 500 past decisions
  2. Compare overall and per confidence band
  3. Read 20 disagreements, decide who was right
  4. High band at 95% or better?
  5. Own flag, off by default
  6. Canary on 5 to 10 units
  7. Roll out in the confident band only

24 use cases, sorted by how well they fit

Start from the strong fits. The amber ones need a measurement before you trust them, and the red ones fail one of the four conditions.
in productionstrong fitmeasure firstpoor fit

Proven in production

  • 1Relevance gate
  • 2Language check
  • 3Classifier fallback

Publishing and content

  • 4Thin-source detector
  • 5Same-event dedupe
  • 6Product fits roundup
  • 7Disclosure present
  • 8Headline quality
  • 9Comment moderation

Commerce and support

  • 10Support-ticket routing
  • 11Return-reason coding
  • 12Review to feature complaints
  • 13Catalogue taxonomy
  • 14Order-fraud pre-triage

Software and AI systems

  • 15LLM guardrail
  • 16RAG passage filter
  • 17Citation check
  • 18Tool and intent routing
  • 19Log-line triage
  • 20PR risk triage

Business ops and home

  • 21Inbox triage
  • 22Expense categorisation
  • 23Lead qualification
  • 24Smart-home intent

Limits, cost and one hard rule

No writing, summarising or extractionPair it with an LLM for the write step.
No world knowledgePut a snippet in the state; a bare name means nothing.
Reads your wording literallyA rewording moved my results about 2 points. Freeze it, re-measure after changes.
Weaker on non-English, maths, datesKeep those checks on an LLM. Early access, hosted API only.
100,000 decisions ≈ $2.50
About 60M input tokens at $0.042 per million, output free, roughly 600 tokens per three-question call. Latency 0.3 to 0.9 seconds.
Never the sole decision-maker for consequences about people. Hiring, credit, medical and legal outcomes stay with a human. Jev can sort and flag. A person decides.
Sources. Model scores, cost per task and speeds: Artificial Analysis, Intelligence Index v4.3.x, including the GPT-6.1 Sol medium, high and xhigh pages, checked 29 September 2026. Astra and Fable scores from the Artificial Analysis v4.3 announcement. Jev figures are my own production measurements, September 2026, rounded. The review-bill example is illustrative. Read the full article on thorstenmeyerai.com.

How Meyer Splits Model Work

The account offers a concrete example of assigning work by task cost and role, rather than choosing a single model for every request. In Meyer’s workflow, a more expensive model handles complex implementation, while a lower-cost model can review meaningful changes routinely. If the cited costs hold for a team’s own tasks, that division could make an additional review pass more practical.

Those implications depend on the task. The index is a measure of general capability, Meyer says, and does not establish which model performs best on a particular team’s code, documents or routing decisions. The article presents his operating choices and benchmark interpretation; it does not report a controlled comparison of his full workflow or measured savings across a team.

The Index Behind His Choices

Meyer bases the model comparisons on the Artificial Analysis Intelligence Index v4.3.x, while noting that it maps general capability rather than settling performance for an individual workload. The cited top-setting scores range from 37 for GPT-6 Luna to 58 for Claude Opus 5.5. The source reports costs per task ranging from $0.07 for Luna to $7.63 for Claude Fable 5.1, but does not explain in the supplied material how each task’s token use was standardized.

His comparison also focuses on effort settings, which change both scores and costs. For Opus 5.5, the source lists $0.55 per task at low effort, $1.34 at medium, $1.82 at high, $3.46 at xhigh and $5.98 at max. Meyer favors high or xhigh for building and says max is rarely worthwhile for his work. GPT-6.1 Sol launched on September 29, according to the source, at the same $2 per million input tokens and $10 per million output tokens as its predecessor.

“The practical reading: Sol is not the model I ask to build. It is the model I can afford to run on everything.”

— Thorsten Meyer

What the Benchmarks Cannot Show

The supplied source does not establish how well these assignments perform across other organizations or workloads. It does not include results from Meyer’s recommended shadow tests, a measured comparison of review accuracy, or an observed total-cost analysis that includes human time. The cost-per-task figures are attributed to the index, but the material provided does not detail the task mix behind them.

Some index settings were also unavailable at publication: Meyer says low and max results for GPT-6.1 Sol had not yet been published. He cautions that a one-point score difference may fall within measurement noise. The source also gives no operational details or benchmark results for Jev, and its final cost example is cut off, so it cannot support a conclusion about total savings after human review.

Test Against Real Workloads

Meyer recommends shadow-testing models on a team’s own tasks before changing assignments. That would let teams compare output quality, review needs, response time and cost under their specific conditions. The source gives no date for further index results or a planned follow-up, so whether new GPT-6.1 Sol effort settings or additional measurements will change Meyer’s choices remains open.

Key Questions

Which three tools does Meyer use most?

He identifies Claude Opus 5.5 for building, GPT-6.1 Sol for detailed work and review, and Jev for high-volume yes-or-no and routing judgments.

Why does Meyer use GPT-6.1 Sol for review?

He says its cited cost of $0.32 to $0.39 per task at high or xhigh makes routine review affordable in his workflow. He also values a reviewer from a different model family, while acknowledging that this does not remove flaws in the shared specification.

Does the index prove which model is best for a team?

No. Meyer describes the Artificial Analysis Intelligence Index as a map of general capability, not a verdict on an individual workload. He recommends testing models against the team’s own tasks.

What remains unknown about Meyer’s approach?

The source does not provide results from his shadow tests, a measured comparison of review quality, or complete cost accounting that includes human review time. It also says some GPT-6.1 Sol effort settings had not yet been published.

Source: ThorstenMeyerAI.com

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