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Head to head · Decision models · October 2026 research run

Drex 1.5 vs Vela 2.0

Drex 1.5 scores 69.7 (B) on agent readiness against Vela 2.0's 66.5 (B), and leads in 5 of 7 scored categories. Vela 2.0 leads on payments & pricing and maintenance & community. Both do decision models.

Best decision models for AI agents · All 91 decisions comparisons

Drex 1.5Nace AI, Inc. (Nace.AI) · Model API B69.7/100#172 of 954 Vela 2.0vLLM Semantic Router project and KR Labs · Model API B66.5/100#291 of 954

Which one, for what

Drex 1.5 B

Best for Routing, triage and yes or no gates inside an agent, where the caller supplies the options and acts on the probabilities. Suited to hosted use at a low per-token price, or to open weights where the licence fits.

Ahead on

  • Reliability, 80 against 57
  • Schema & documentation, 88 against 78
  • Agent ergonomics, 85 against 79
  • Security & auth, 65 against 60
  • Transparency & trust, 63 against 48

Also in its favour

  • A hosted endpoint, with nothing to install

Watch for

The rank 1 claim comes from Nace's own run on Decision Index 0.3.1, and Drex is not on the public board for 0.3 or 0.2.1.

Vela 2.0 B

Best for Self-hosted routing and guardrail checks in one call, where span offsets for personal data or unsupported claims matter.

Ahead on

  • Payments & pricing, 60 against 40
  • Maintenance & community, 84 against 65

Also in its favour

  • No key needed to call it
  • Open source

Watch for

No version tags on the four Hub repositories, and the 4B and 9B weights were replaced in place on 3 October 2026

Score by category

CategoryWeight this runDrex 1.5Vela 2.0Edge
Reliability16%208057Drex 1.5 +23
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28878Drex 1.5 +10
Agent ergonomics13%16.28579Drex 1.5 +6
Security & auth14%17.56560Drex 1.5 +5
Payments & pricing10%12.54060Vela 2.0 +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.86584Vela 2.0 +19
Transparency & trust7%8.86348Drex 1.5 +15
Negative events≤15-20
TotalB 69.7/100B 66.5/100

Facts side by side

FactDrex 1.5Vela 2.0
KindModel APIModel API
VendorNace AI, Inc. (Nace.AI)vLLM Semantic Router project and KR Labs
Hosted endpointhttps://console.nace.ai/v1/systemoneno (local only)
TransportsHTTPHTTP
AuthAPI keyNone
PricingFreemiumFree
x402nono
LicenceHosted API under the Nace AI Terms of Service, last updated 5 May 2026. Weights under the Nace AI Open RAIL-M licence (modified, version 1.0, October 2026), which is not an open-source licence. Businesses above $1 million in revenue or funding need a separate commercial licence, and competing products are excluded. The bundled code/kev package, derived from Jared Palmer's Kev (https://github.com/jaredpalmer/kev), and the GitHub repository are Apache-2.0, and the agent skill is MIT.Apache-2.0 (weights, code and documentation). The 0.3B's tokeniser keeps the Gemma Terms of Use, and training data keeps its own licences
Read-only variant documentednono
llms.txtyesno
Last release2026-09-282026-10-06
Terms last updatedno document linked
Privacy policy last updatedno document linked
Customer content may train models
Terms restrict automated access
Terms restrict benchmarking
Terms or service can change without notice
Arbitration or class-action waiver
Popularity318 npm/wk, 156 PyPI/wk6.1k stars

Verdicts

Drex 1.5

The hosted endpoint has a public OpenAPI document, published limits and pinned model versions, at $0.05 per million input tokens with no output charge. The #1 under 10B claim rests on Nace's own run, since Drex is absent from both public boards. Weights carry Open RAIL-M, which requires a commercial licence above $1 million in revenue or funding.

Vela 2.0

One self-hosted call answers routing, prompt-attack, personal-data and unsupported-claim questions with probabilities and character offsets, under Apache-2.0 with SHA-256 manifests. The models are days old and carry no Hub version tags, and the three larger sizes keep 74 to 89 per cent of their Decision 2.0 bases on the Jev Decision Index by the authors' figures.

Before you call either

Drex 1.5

  1. Call https://console.nace.ai/v1/systemone with Authorization: Bearer nace_sk_..., and pin model drex-v1.5 rather than drex-latest in production.
  2. Stop on 402 insufficient_credit or 402 payment_required until credit is topped up or the unpaid invoice is paid.
  3. Retry 429 and 529 after retry-after-ms. On a 422 for an unknown model, use one of the ids the error message lists.
  4. Keep state below 131,072 tokens and the body below 1,048,576 bytes, and send at most 512 questions per request.
  5. Keep the key on a server. A key in browser code is exposed, and the /v1 routes send no Access-Control-Allow-Origin header.
  6. Check usage.input_tokens and the usage CSV after retries, since /v1/systemone documents no idempotency key.

Vela 2.0

  1. Pin a commit hash with revision= when loading from the Hub. The repositories have no tags and main has changed since launch
  2. Send the served name in model, for example vllm-sr/Vela-2.0-4B. The bundled server answers 422 to any other name
  3. Name span questions pii, halu or toxic, or set "head": "router", to get the trained router head. Other labels go to the broad head
  4. Keep input under 16,384 tokens a sequence (8,192 on the 0.3B). The bundled server answers 413 when the questions alone don't fit
  5. Set VELA2_API_KEY before binding the bundled server beyond 127.0.0.1, and keep the model runtime on a trusted network

Questions

Which is better for AI agents, Drex 1.5 or Vela 2.0?

Drex 1.5 scores 69.7 (B) on agent readiness against Vela 2.0's 66.5 (B), and leads in 5 of 7 scored categories. Vela 2.0 leads on payments & pricing and maintenance & community.

Do Drex 1.5 and Vela 2.0 need an API key?

Drex 1.5 needs an API key. Vela 2.0 needs no key.

Can an agent call Drex 1.5 and Vela 2.0 without installing anything?

Drex 1.5 has a hosted endpoint at https://console.nace.ai/v1/systemone. No hosted endpoint is listed for Vela 2.0.

Are Drex 1.5 and Vela 2.0 open source?

No open-source release is listed for Drex 1.5. Vela 2.0 is open source (Apache-2.0 (weights, code and documentation). The 0.3B's tokeniser keeps the Gemma Terms of Use, and training data keeps its own licences).

Other comparisons with Drex 1.5 or Vela 2.0

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