Jev Use
Typed yes/no, pick-one and score judgments from Jev in one batched call; typed escalation back.
Runs on your machine from its package; the steps are below.
What it does
- Reads
- Writes
- High impact
At most: only reads or looks up information.
What it costs
FreeOdel charges nothing per call. The publisher may charge for its own service.
Runs locally over stdio
This server isn't hosted — your MCP client launches it from a package registry. Use one of the commands below, or drop the config into your client (e.g. Claude Desktop).
Run
npx -y jev-use
MCP client config
{
"mcpServers": {
"jev-use": {
"command": "npx",
"args": [
"-y",
"jev-use"
]
}
}
}English | 简体中文
The best way for Claude Code, Codex, and pi to work with Jev: hand the tasks that need no text output to Jev — faster steps, fewer tokens, tasks done sooner and better.
It makes the LLM and Jev true collaborators: when content needs to be written, the LLM takes over; when a step just needs a fast decision, Jev executes it.
Demos — real runs, 1× speed
| Directions task: Jev clicks, the LLM types — 10 decisions (p50 274 ms) · 4 writes; Jev rejects a wrong route, the LLM rewrites | Context compaction — 200 messages judged in 7 calls, one LLM paragraph replaces the dropped pile; recall 3/3 |
Pong: ball speed = decision latency — 86 Jev decisions in 20 s vs 6 (haiku) and 3 (gemini) called the usual way; enum-constrain both and the gap is 3× | Gate every shell command — dangerous ones denied in ~230 ms with a reason, zero LLM tokens |
Every demo is a rerunnable script in bench/examples/; all numbers, methodology, variance and caveats: bench/RESULTS.md · third-party measurements: docs/evidence.md.
Install
npx -y jev-use install # wires Claude Code, Codex, and pi — whichever it finds
Set one key in the environment your agent runs in (JEV_BACKEND=mock for
a keyless dry run):
| Provider | Env var |
|---|---|
| TypeSafe direct | TYPESAFE_API_KEY |
| OpenRouter | OPENROUTER_API_KEY |
| Vercel AI Gateway | AI_GATEWAY_API_KEY |
npx -y jev-use doctor checks the wiring. Judged state goes to the
provider you configure; JEV_BACKEND=mock stays local. Plugin form with
the routing skill and the PreToolUse gate:
harness/claude-code ·
harness/codex.
Use as a library
npm i jev-use — zero runtime dependencies on the judgment path:
import { Jev, check, pick, rate } from "jev-use";
const jev = new Jev();
const { answers } = await jev.judge(state, {
next: pick("Next action?", { merge: "all green", rerun: "looks flaky", hold: "needs attention" }),
risk: rate("How risky?", ["routine", "worth a look", "incident"]),
passed: check("Did the run fully succeed?"),
});
// answers.next → { answer: "merge", confidence: 0.93, confidenceFrom: "reported", escalate: false }
Anything Jev can't or shouldn't decide comes back with escalate: true
and a typed reason. Tools, verdict shape, escalation contract, CLI:
docs/reference.md.
Small enough to read
| File | Job |
|---|---|
| src/protocol.ts | Questions (check/pick/rate), verdicts, escalation reasons |
| src/dispatch.ts | Pre-call routing: what never reaches Jev |
| src/judge.ts | screen → backend → hand back what is unsure; gate |
| src/jev.ts | The Jev client over that engine |
| src/redact.ts | Credentials stripped from a gated action before it is sent |
| src/backends/ | TypeSafe, OpenRouter, Vercel, mock adapters |
| src/server.ts | The two MCP tools |
| src/cli.ts | install, serve, hook gate, doctor |
| skills/jev-use/SKILL.md | The routing rules the agent follows |
Development
$ npm run typecheck && npm test # unit tests incl. per-provider wire fixtures
$ npm run smoke # real MCP client ↔ built CLI over stdio
$ node bench/run.mjs # micro-benchmarks, your key and region
Substantially written with Claude Code (AI-assisted).
MIT © shitianfang
