Integration
Jev MCP Server
jev-mcp is a community MCP server that gives coding agents twelve typed decision tools powered by Jev. It runs over npx, needs Node.js 22+, and works with any System One-compatible endpoint — including jev-api.org, which bills 1 credit per successful request.
Updated
What jev-mcp is
jev-mcp is an open-source MCP server by jkudish, published under the MIT license and distributed as the npm package @jkudish/jev-mcp. It is a community project, not a TypeSafe product. Once installed, your agent — Claude Code, Codex, Amp, or any MCP-capable client — can call Jev to verify claims, screen text, rerank candidates and gate patches without writing glue code.
The server speaks to a System One-compatible endpoint. Set JEV_PROVIDER=compatible and JEV_API_BASE_URL to the full POST URL — for this site https://jev-api.org/v1/systemone — plus JEV_API_KEY with a jev-api.org key. JEV_MCP_MODEL defaults to jev-latest.
The twelve tools
Each tool wraps one or more typed questions, so the agent gets a probability or a pick instead of a paragraph.
| Tool | What it does |
|---|---|
| jev_verify | Checks claims against evidence and returns a probability. |
| jev_screen | Judges fetched text, including a prompt-injection probability. |
| jev_noul | Answers a bare yes/no question. |
| jev_find | Picks the best candidate from a list by meaning. |
| jev_rerank | Reranks candidates against a query. |
| jev_classify | Applies batch labels to items. |
| jev_decide | Chooses among bounded alternatives. |
| jev_compare | Describes how two passages relate. |
| jev_extract | Pulls field values with regex plus judgment. |
| jev_audit | Audits extracted values against the source. |
| jev_review | Scores a proposed diff. |
| jev_gate | Reviews a patch plus completion claims before merge. |
Install per client
The server itself is npx -y @jkudish/jev-mcp. Wire the environment variables into whichever client you use:
# Claude Code
JEV_PROVIDER=compatible \
JEV_API_BASE_URL=https://jev-api.org/v1/systemone \
JEV_API_KEY=jeva_... \
claude mcp add jev -- npx -y @jkudish/jev-mcp
# Amp
amp mcp add jev -- npx -y @jkudish/jev-mcp# ~/.codex/config.toml
[mcp_servers.jev]
command = "npx"
args = ["-y", "@jkudish/jev-mcp"]
[mcp_servers.jev.env]
JEV_PROVIDER = "compatible"
JEV_API_BASE_URL = "https://jev-api.org/v1/systemone"
JEV_API_KEY = "jeva_..."{
"mcpServers": {
"jev": {
"command": "npx",
"args": ["-y", "@jkudish/jev-mcp"],
"env": {
"JEV_PROVIDER": "compatible",
"JEV_API_BASE_URL": "https://jev-api.org/v1/systemone",
"JEV_API_KEY": "jeva_..."
}
}
}
}Cost on jev-api.org
Every tool call sends at least one API request, and on this site each successful request uses 1 credit. An agent that verifies, screens, and gates in one task may therefore spend several credits — keep an eye on how often the agent reaches for a tool.
There is also an optional HTTP mode: start the server with --http and it serves /mcp. Unless it binds to loopback, you must set JEV_MCP_AUTH_TOKEN so the endpoint is not left open.
FAQ
Do I need a TypeSafe key for jev-mcp?
Not when you run it against this site. Set JEV_PROVIDER=compatible, JEV_API_BASE_URL=https://jev-api.org/v1/systemone and JEV_API_KEY to a key from your jev-api.org dashboard.
Which Node.js version does it need?
Node.js 22 or newer. The server runs through npx -y @jkudish/jev-mcp, so no permanent install is required.
Is jev-mcp an official TypeSafe project?
No — it is a community project by jkudish under the MIT license. It works with any System One-compatible endpoint, including this site's /v1/systemone.
How much does an agent session cost?
Each tool call makes at least one API request; a successful request on this site uses 1 credit, so cost scales with how many tools the agent invokes per task.
Give your agent Jev
Create a key, set the three environment variables, and the twelve tools are live in your next session.