Decision model vs LLM for routing: when to use Jev, Laya, or Clef

Key takeaways

• LLM: generate, plan, explain, open tools.
• Decision model: closed Choice / Score / Noul with native probabilities.
• Swap the “JSON classify” LLM call for Jev, Laya, or Clef when volume is high.
• Keep an LLM in the loop for gray-zone explanation and user-facing text.
• Last verified: October 2026.

Table of contents

1. The confusion
2. Side-by-side
3. Decision tree
4. Example stacks
5. Related guides
6. FAQ

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The confusion

Teams say “we use GPT for routing” when they mean “we ask GPT for a label and hope the JSON parses.” That works in a demo. Under load it is latency, spend, and silent schema drift.

For builders, the useful split is:

If the program needs a paragraph, use an LLM. If the program needs a branch, use a decision model.

Category primer: what is a System One decision model.

Side-by-side

Job	Prefer LLM	Prefer decision model
Write the user reply	Yes	No
Pick support queue from 8 teams	Overkill	Yes
Multi-hop research then choose	Yes (then maybe decide)	Alone, weak
p(destructive) before shell	Expensive	Yes
Explain why it routed	Yes	No (no prose)
Score urgency 1 to 5	Possible	Better fit
Classify screenshot UI state	Vision LLM or Clef	Clef if typed

Decision tree

1. Can you name the allowed answers in advance? If no, LLM (or human).
2. Do you need prose out? If yes, LLM.
3. Is this called more than a handful of times per user action? Lean decision model.
4. Do you need pixels in state? Prefer Cloudflare Clef.
5. Must weights stay in your network? Prefer Laya or self-hosted Clef.
6. Want managed API + SDKs with minimal ops? Prefer Jev.

Example stacks

Support desk: Laya or Jev triage → human or LLM draft → send.

Coding agent: LLM plans and edits → Jev model route + tool Choice + risk Noul each step. Details: Jev for coding agents.

Edge trust & safety: Clef-flash Score on Workers → block or queue → LLM only for appeals copy.

Growth inbound: decision-model lead Score → CRM; LLM writes the first email only for high-fit leads.

Related guides

Guide	Why
Top 10 Jev use cases	Concrete Jev patterns
Top Laya use cases	Open-weight patterns
Top Cloudflare Clef use cases	Multimodal patterns
Jev vs Laya vs Clef	Vendor pick

FAQ

See frontmatter FAQ for schema-ready Q&A (also rendered on the live guide page).