Green Shield MCP — Opnli Green Shield Files

A reference MCP tool that asks a human before every action.

Green Shield Files gives an AI host (such as Claude Desktop) three file tools: list, read and move. Before any of them runs, a Green Shield card appears on opn.li for the human who owns the tool. They choose Allow or No. The decision is written to their tamper-evident chain on the Openly Trusted Network (OTN) first. The tool acts only when it holds that record. No answer within the time limit means No.

It is part of the Open Consent Project and follows the Human Consent Layer (HCL) standard.

Status (October 2026): proven in Claude Desktop (1 October 2026) and, in private testing through OpenAI's Secure MCP Tunnel, in ChatGPT (22 October 2026). Tested on macOS only.

Ten-minute quickstart (macOS)

You need: macOS, Node.js (tested with version 24), Claude Desktop, and an opn.li membership. Opnli membership is free. If you do not have one yet, the opn.li page that opens in step 3 lets you create it, and the tool then finishes linking on its own.

1. Get the code (1 minute)

git clone https://github.com/mikeoz/green-shield-mcp.git
cd green-shield-mcp
npm install

2. Make the Green Shield folder (1 minute)

The tool can reach only one folder. By default that is GreenShieldTest in your home folder. A path outside it is refused at once, with no card.

mkdir -p ~/GreenShieldTest
echo "hello from the Green Shield" > ~/GreenShieldTest/hello.txt

To use another folder, set GS_FILES_ROOT in step 4.

3. Link the tool to your membership (2 minutes)

node link.js

Your browser opens opn.li. Sign in, or create your free account. Terminal then shows LINKED: Green Shield Files.

What just happened: opn.li handed your sign-in to this computer only. link.js used it once to register the tool on the network, with you as its owner, and saved only the tool's own badge to ~/.green-shield-files/badge.json (readable only by you). Your sign-in is never stored. The badge is how the network knows which tool is asking, and that the cards go to you.

4. Add the tool to Claude Desktop (3 minutes)

Open Claude Desktop → Settings → Developer → Edit Config, and add (with your own path to server.js):

{
  "mcpServers": {
    "opnli-green-shield-files": {
      "command": "node",
      "args": ["/full/path/to/green-shield-mcp/server.js"]
    }
  }
}

Optional settings, under "env": GS_FILES_ROOT (the folder) and GS_CONSENT_URL (the network address; default https://consent.opn.li).

Restart Claude Desktop.

5. See the Green Shield (3 minutes)

1. Open opn.li/consent in your browser and stay signed in.

2. In Claude Desktop, ask: "List the files in my Green Shield folder."

3. A card appears on opn.li naming the tool and the action, with a four-letter match code. The same code appears in the tool's answer, so you know the card and the request belong together.

4. Choose Allow once. Claude shows the file list.

5. Ask again and choose No. Nothing is read, and Claude is told it was refused.

Related MCP server: mcp-local-access

How it works

The tool waits up to 95 seconds for a decision. The card itself expires sooner, and an expired card is a No.

Make your own Green Shield tool

server.js is a small, readable example. To protect your own tool:

• Change the tool name in link.js (entity_name) and the server name in server.js.

• Keep the pattern: ask the network first, act only with a receipt, treat every error as No.

A step-by-step guide for adding the Green Shield to an existing MCP server is in preparation.

Known limits

• link.js opens the browser with the macOS open command; Windows and Linux are not yet supported.

• Waiting cards are held in memory on the network; a network restart turns a waiting card into a No.

License

Apache 2.0 — see LICENSE. Copyright 2026 Opnli Corporation. The Opnli Green Shield logo in assets/ is a mark of Opnli Corporation; the license covers the code, not the brand.

Only a human can give consent. Consent requires context. CARDs provide context. The Human Consent Layer enforces the decision.