How I Assign AI Tasks Across Opus, Sol, And Jev
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🔍 Read the full analysis: How I Assign AI Tasks Across Opus, Sol, And Jev on ThorstenMeyerAI.com

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TL;DR

Thorsten Meyer says he uses Opus 5.5 for building, GPT-6.1 Sol for detailed review and Jev for high-volume yes-or-no decisions. His comparison, based mainly on Artificial Analysis Intelligence Index v4.3.x, weighs task costs as well as scores; it does not establish which model performs best on every workload.

Thorsten Meyer says he assigns software building to Claude Opus 5.5, detailed investigation and review to GPT-6.1 Sol, and high-volume yes-or-no decisions to Jev, a decision model that cannot write sentences. In his Sept. 29 account, Meyer argues that per-task costs vary widely among models with relatively close benchmark scores, making the choice of model and effort setting a practical cost decision for teams using AI.

In the comparison Meyer published Sept. 29, he cites the Artificial Analysis Intelligence Index v4.3.x for general capability scores and task-cost estimates. The index’s listed top settings put Opus 5.5 at 58 points and an estimated $5.98 per task, and GPT-6.1 Sol at xhigh at 51 points and $0.39. These are index results, not measurements of Meyer’s production workload. Meyer cautions that the index should not be treated as a verdict on any particular use case.

Meyer describes a division of work based on those trade-offs. He says he uses Opus 5.5 at high for features, APIs, multi-file work and refactors, and xhigh for harder work such as architecture, migrations and trust boundaries. He assigns Sol at high or xhigh to focused file or code-diff investigations and independent review. He says Astra or Fable provide second opinions when Sol and Opus disagree; Sonnet handles scoped subtasks, while Luna is used for classification, extraction and routing.

The Artificial Analysis estimates change with the effort setting. Its index lists Opus at 54 points and $1.82 per task at high, compared with 58 points and $5.98 at max. Meyer says he rarely uses max. He identifies Sonnet’s high setting, at 47 points and $1.08, as its best value among the listed results; its max setting costs $7.60 for a score of 56. These are index estimates, not a guarantee of equivalent quality or savings in other work.

At a glance
reportWhen: Published Sept. 29, 2026; GPT-6.1 Sol a…
The developmentThorsten Meyer published a model-by-model task allocation on Sept. 29, 2026, including GPT-6.1 Sol, which he says was released that day.

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 Task Costs Shape Model Choice

Meyer’s approach shifts model selection from a single ranking to a cost-per-task decision. If a cheaper model meets a team’s quality bar for routine classification or review, using the most expensive available model for every step could add cost without a matching benefit. Conversely, a higher-scoring model may be justified for complex work where errors or rework carry greater consequences.

Meyer also argues that an inexpensive review pass can make a different model family practical as a second set of eyes. He says another model may catch issues the builder misses. That is his rationale for review, not proof that a model’s review is independent or sufficient: the reviewer can share assumptions embedded in the same brief, and Meyer says human judgment remains part of his process.

Meyer cautions that token prices alone do not measure the full cost of work. He says human review time can outweigh a model-price saving, though his example is explicitly illustrative rather than measured. The figures therefore frame a purchasing and workflow question; they do not show realized savings for a particular company.

The Scores Behind Meyer’s Stack

According to the figures Meyer attributes to the Artificial Analysis Intelligence Index, six models sit within about 20 index points of one another while their estimated task costs differ by roughly 100 times. The table he cites lists Opus 5.5, released Sept. 22, with a score of 58 and cost of $5.98 per task; Sonnet 5.5, released Sept. 28, at 56 and $7.60; and Fable 5.1, released Sept. 1, at 53 and $7.63. It lists GPT-6 Astra at 53 and $3.26, GPT-6.1 Sol at 51 and $0.39, and GPT-6 Luna at 37 and $0.07.

Meyer says GPT-6.1 Sol launched Sept. 29 at the same listed token prices as its predecessor: $2 per million input tokens and $10 per million output tokens. The Artificial Analysis index lists medium, high and xhigh settings for the model. Meyer reports their respective scores as 48, 50 and 51, and estimated task costs as $0.21, $0.32 and $0.39. He says the index has not yet published Sol’s low or max settings.

Meyer reports that, in the index results, moving Opus from xhigh to max adds two points while raising estimated task cost by 73%. From medium to max, he reports a 4.46-fold cost increase for seven points. Those comparisons apply to the specific index results and settings he cites; benchmark points alone do not establish how much better a model will perform on a given assignment.

What the Benchmark Cannot Settle

The comparison Meyer published does not show how the models perform on his own tasks or another organization’s workload. He recommends shadow-testing before switching, but provides no results from such a test. He also says a one-point score difference falls within the noise, so small gaps should not be read as decisive evidence of a capability advantage.

Several factors remain unresolved in Meyer’s account: the index’s estimates may not match an organization’s actual prompts, output lengths or pricing; he does not detail how its task-cost figures were calculated; and Sol’s low and max effort results are not yet listed. His statements about which models suit particular roles describe his current practice and judgment, rather than controlled comparisons across users.

Meyer says Sol’s high and xhigh settings take 57 to 69 seconds to produce a first token in the index. That is a reported benchmark measurement, not a promise of response time in every product or setup. His account does not say whether that delay is acceptable for all the review tasks he assigns to Sol.

Test the Split on Real Work

Meyer recommends that teams considering a similar arrangement shadow-test candidate models against their existing workflow before making a switch. That would let teams compare quality, task costs and review time on representative assignments. He does not announce a formal trial, release schedule or further benchmark update.

For his own process, Meyer says a failed review should go back to Opus with the failing case and supporting evidence, rather than a vague instruction to try harder. He also says passing tests should not be treated as approval to ship by themselves. His account does not specify what review criteria he applies beyond that guidance.

Key Questions

Which model does Meyer use to build software?

He says Opus 5.5 at high is his main setting for features, APIs, multi-file work and refactors. He uses xhigh for harder assignments such as architecture, migrations and trust boundaries.

What does Meyer use GPT-6.1 Sol for?

He assigns Sol at high or xhigh to focused investigations and independent review of files or code diffs. He says its estimated index cost is $0.32 to $0.39 per task at those settings.

Does the benchmark show which model is best for every team?

No. The Artificial Analysis index measures general capability, and the source says teams should shadow-test models on their own work before switching. Its task costs and scores may not predict results for a particular workload.

Why does Meyer rarely use Opus at max effort?

The index lists Opus at $5.98 per task and 58 points at max, compared with $3.46 and 56 points at xhigh. Meyer says the additional cost is rarely worthwhile for his assignments.

Source: ThorstenMeyerAI.com

This content is for general information only and is not financial, tax or legal advice. Consult a qualified professional for decisions about your money.
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