How I Split AI Work Between Opus, Sol, And Jev
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🔍 Read the full analysis: How I Split AI Work Between Opus, Sol, And Jev on ThorstenMeyerAI.com

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TL;DR

Thorsten Meyer’s Sept. 29 report assigns Opus 5.5 to building, GPT-6.1 Sol to detailed review and Jev to high-volume yes-or-no decisions. The approach weighs benchmark scores against estimated cost per task, while the report says the figures do not establish which model will perform best on every workload.

In a report dated Sept. 29, 2026, Thorsten Meyer said he uses Claude Opus 5.5 for software building, GPT-6.1 Sol for detail work and review, and Jev for high-volume yes-or-no and routing decisions. The split reflects a cost-and-capability calculation based on Artificial Analysis benchmark data; it matters to teams deciding whether to use one model for every task or route work among several.

Meyer identifies Opus 5.5 at high effort as his main model for features, APIs, multi-file work and refactors. He gives it an Intelligence Index score of 54 and an estimated cost of $1.82 per task. For architecture, migrations and trust-boundary work, he uses xhigh: a score of 56 at $3.46 per task. At the max setting, Opus scores 58 and costs $5.98 per task.

He assigns GPT-6.1 Sol to close examination of files and code changes, and to review work produced by Opus. The report lists Sol at $0.32 per task on high and $0.39 on xhigh, with index scores of 50 and 51. Meyer says that price makes it practical to run a review on each meaningful change. He describes Jev as unable to write prose, using it instead for high-volume binary decisions and routing; the supplied material gives no benchmark score or per-task price for Jev.

The report lists six models and settings in its comparison: Opus 5.5, Sonnet 5.5, Fable 5.1, GPT-6 Astra, GPT-6.1 Sol and GPT-6 Luna. It says their top-setting scores span 37 to 58, while listed costs range from $0.07 to $7.63 per task. Meyer recommends Sonnet at high effort for scoped work such as documents and slides, and Luna for classification, extraction and routing. Astra and Fable are alternatives when task-specific tests favor them.

At a glance
reportWhen: Published Sept. 29, 2026; GPT-6.1 Sol w…
The developmentThorsten Meyer published a model-by-model workflow that assigns building, review and routing tasks to Opus 5.5, GPT-6.1 Sol and Jev, citing benchmark scores and estimated costs.
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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.

Why Meyer Adds a Review Model

The workflow treats model choice as a task-level cost decision. Meyer argues that paying for the highest available setting across all work can raise costs sharply for small score gains. In his figures, Opus rises from $1.82 per task at high effort to $5.98 at max, a 73% increase from xhigh to max for two additional index points. He also reports Sonnet 5.5 at max costing $7.60 per task for a score of 56, compared with Opus at 58 for $5.98.

A separate model reviewing generated work may catch issues the authoring model misses, and Meyer says the lower listed cost of Sol makes repeated reviews affordable in his workflow. That is his operational judgment, not evidence that a second model will reliably find defects. He cautions that review quality depends on the requirements and evidence provided: two models can share the same mistaken assumptions, and passing tests alone do not settle whether a change should ship.

The cost figures also put human review time in the calculation. Meyer says even a small saving on model charges can be erased by an extra minute of human review, but labels that example illustrative rather than measured. The practical outcome will depend on task complexity, correction rates and how much oversight a team needs.

The Benchmarks Behind the Split

Meyer says the scores come from the Artificial Analysis Intelligence Index v4.3.x, except where otherwise noted. He describes it as a map of general capability rather than a verdict on a reader’s workload, and advises shadow-testing before switching systems. The figures in the report are presented as estimates for defined benchmark tasks, not as a guarantee of production cost or output quality for a particular team.

The report’s effort-level table shows that settings change both scores and costs. For Opus 5.5, the listed score moves from 42 at low effort to 58 at max, while estimated task cost rises from $0.55 to $5.98. For Sonnet 5.5, the score moves from 36 to 56 and cost from $0.41 to $7.60. Meyer favors medium for everyday documents and high for Sonnet’s scoped work; he says max is rarely justified in his use.

For GPT-6.1 Sol, the report says Artificial Analysis listed medium, high and xhigh settings when it was published. Medium scored 48 at $0.21 per task, high scored 50 at $0.32 and xhigh scored 51 at $0.39. Meyer compares Sol xhigh with Astra and Fable, whose listed scores are one or two points higher, while their stated task costs are substantially greater. He notes that a one-point gap may fall within measurement noise.

Limits of the Cost Comparison

The supplied report does not include the benchmark methodology, uncertainty ranges or enough detail to independently reproduce its per-task cost estimates. It does not define Jev’s provider, price, evaluation results or routing accuracy. Its figures should therefore be read as the report’s account of one benchmark and workflow, not as independently verified results for every use case.

Some measurements may also change as model settings and benchmark listings are updated. Meyer says the index had not published low or max results for GPT-6.1 Sol at the time of writing. He reports first-token delays of 57 seconds at high and 69 seconds at xhigh, which may limit interactive use, but the material does not describe the full testing conditions or how those delays vary across workloads.

The report does not provide a controlled comparison of the complete workflow against a single-model setup. It remains unclear how often Sol catches errors, how many Opus outputs need rework, or whether the savings in model charges outweigh added review and routing overhead for other teams.

Test the Workflow on Real Tasks

Meyer’s stated next step for readers is to shadow-test models on their own work before changing defaults. A team could compare outputs against its existing process, track error rates and review time, and record total cost per completed task rather than relying on index scores alone. Those results would help determine whether Opus, Sol, Jev or the listed alternatives fit particular tasks.

The report does not announce a formal follow-up test or a date for updated results. Further detail on Jev’s performance, the benchmark’s assumptions and the treatment of human review would help readers assess the full workflow. Until those details are available, the model assignments remain Meyer’s reported practice and a proposal to evaluate against local requirements.

Key Questions

What jobs does Meyer assign to Opus 5.5?

He uses Opus 5.5 at high effort for features, APIs, multi-file changes and refactors. He reserves xhigh for harder work such as architecture and migrations.

Why does he use GPT-6.1 Sol for review?

The report lists Sol at $0.32 per task on high and $0.39 on xhigh. Meyer says that cost makes a separate review pass practical in his workflow; the report does not show that Sol will catch every error.

What does Jev do in the workflow?

Meyer describes Jev as a decision model that cannot write a sentence. He uses it for high-volume yes-or-no decisions and routing, but the supplied report does not provide its benchmark score or price.

Do the benchmark scores show which model is best for every team?

No. Meyer says the Artificial Analysis Intelligence Index measures general capability and is not a verdict on a particular workload. He advises testing models against a team’s own tasks before making a switch.

Source: ThorstenMeyerAI.com

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