jev-mcp-open-source
Self-hosted Jev MCP gateway on Cloudflare Workers with nine tools for intent routing, reranking and batch judgments.
Overview
Jev MCP for Cloudflare is a self-hosted MCP gateway running on Cloudflare Workers with D1 storage. It wraps TypeSafe's System One model (jev-latest) as nine tools for judgment-style work: route_intent, rerank_candidates, batch_judge, select_values, verify_evidence (support, refute or insufficient), evaluate_options with code-weighted ranking, classify_hierarchy that stops when uncertain, decide_next_step, and a raw system_one passthrough. A companion Codex skill tells the assistant when to call it. The main README is in Chinese with an English version.
TypeSafe keys are stored encrypted with AES-GCM in D1 and rotated, and an /admin console manages keys and usage. Batch tools cap at 10 records, 128 KB input and concurrency 3; failed records are marked failed rather than dropped, and calls are not retried. The README warns that the /mcp endpoint has no authentication by design, so anyone who knows the URL can spend your credit.
What the decision model decides
| Type | Question | Answers |
|---|---|---|
| Choice | route_intent: which path, tool or knowledge source should handle this request? | — |
| Score | rerank_candidates: how relevant is each retrieved snippet? | — |
| Choice | verify_evidence: does the evidence support, refute or not decide the claim? | support · refute · insufficient |
How it works
- Deploy the Worker and D1 database with Wrangler
- Add TypeSafe keys through the /admin console
- Point an MCP client such as Codex at /mcp
- The assistant calls a tool; the Worker calls System One with a rotated key
- Structured answers with confidence return; failures are marked, not retried
Strengths
- Keys encrypted at rest and rotated
- Usage tracking per key
- Failure isolation in batches without double billing
- Eval cases included for format and live checks
Caveats
- The /mcp endpoint is unauthenticated by design
- Batch limits of 10 records per call
- Live eval is not a domain accuracy guarantee, as the README notes
Getting started
npm ci, copy wrangler.example.jsonc, create a D1 database, apply migrations, set ADMIN_TOKEN and KEY_ENCRYPTION_SECRET, then npm run deploy.At a glance
- Type
- MCP server
- Status
- beta
- Language
- TypeScript
- Runtime
- Cloudflare Workers MCP gateway
- Has code
- yes
- Has tests
- yes
- License
- MIT
Use cases and integrations
How curated lists describe it
Self-hosted Jev MCP on Cloudflare Workers with intent routing, retrieval reranking and batch judgments
logicrw/awesome-jev-projects
Frequently asked questions
What tools does the gateway expose?
Nine tools including intent routing, reranking, batch judging, evidence verification, hierarchical classification and a raw System One passthrough.
Is the endpoint secured?
Only /admin requires a token; the README warns /mcp is open and should be treated as semi-public or protected at the Cloudflare level.
Where are API keys stored?
Encrypted with AES-GCM in Cloudflare D1, showing only the last four characters.
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