@proof-layer/mcp

Cryptographic AI governance for any MCP-aware host. Drop signed, hash-chained, independently verifiable receipts into Claude Desktop, Cursor, Cline, or any other Model Context Protocol client with a single config entry.

Built by WORLD999_LABS. Renamed from @veridocs/mcp (April 2026). Legacy VERIDOCS_* environment variables are still accepted — see Migration below.

npx -y @proof-layer/mcp

What this is

@proof-layer/mcp is the official MCP server for Proof Layer — the cryptographic governance layer for AI agents. Once installed, it gives any MCP-aware AI assistant the ability to:

• Submit agent action proposals for governance evaluation before they execute
• Receive signed EXECUTE / BLOCK / REVIEW / SHADOW verdicts
• Retrieve and cryptographically verify receipts on demand
• Create and operate under scoped, time-bounded delegation plans

Every receipt is Ed25519-signed, hash-chained, and independently verifiable offline using only the published public key at /v1/public-key. For client-side verification with zero dependencies, install @proof-layer/verify.

Quick start — Claude Desktop

Add this block to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "proof-layer": {
      "command": "npx",
      "args": ["-y", "@proof-layer/mcp"],
      "env": {
        "PROOF_LAYER_API_KEY": "pl_live_...",
        "PROOF_LAYER_API_URL": "https://prooflayer.world999labs.com"
      }
    }
  }
}

Restart Claude Desktop. Ask: "List my recent Proof Layer receipts." — Claude will call pl_list_receipts and return your audit chain.

Get an API key at prooflayer.world999labs.com.

Cursor / Cline / other MCP hosts

The same command / args / env block works in any MCP-aware host. Place it in the host's MCP server configuration file under whatever key the host uses (e.g. mcpServers in Cursor).

Environment variables

Legacy VERIDOCS_* environment variables are still read if the corresponding PROOF_LAYER_* variable is unset. Existing Claude Desktop configurations using VERIDOCS_API_KEY continue to work without modification. New installs should use the PROOF_LAYER_* names.

Telemetry & privacy

This package sends one anonymous install ping on startup, plus periodic anonymous heartbeats while running. The ping contains:

• A locally-generated random install ID (cannot be linked back to you)
• The package version (e.g. 1.0.0)
• The MCP host name (e.g. claude-desktop, cursor, cline)
• Your operating system family (e.g. darwin, linux, win32)
• Approximate country code derived from your IP (e.g. US, DE)

We do not collect: your IP address (only the derived country, then discarded), your name, your email, your prompts, your receipts, your API key, your file paths, your machine name, or any other environment variables.

To disable, add "PROOF_LAYER_TELEMETRY": "off" to the env block in your MCP host config. (Legacy "VERIDOCS_TELEMETRY": "off" still works.) The flag is checked on every startup.

The install ID is stored at ~/.proof-layer/install-id. If you previously ran @veridocs/mcp, the existing ID at ~/.veridocs/install-id is migrated forward on first run so install identity is preserved across the rename.

Raw pings are retained for 90 days then aggregated and deleted. Full policy: PRIVACY.md.

The @proof-layer/verify package sends nothing — it runs entirely offline.

Tools exposed

The server registers eight tools, all prefixed pl_:

Full schema for each tool is exposed via ListToolsRequestSchema — your MCP host will discover them automatically.

How it fits

Your AI assistant (Claude Desktop / Cursor / Cline)
        ↓ MCP (stdio)
@proof-layer/mcp                       ← this package
        ↓ HTTPS
Proof Layer kernel
        ↓
Signed receipt → hash chain → verifiable offline

Before any consequential action — sending email, modifying data, executing payment, deleting records — the assistant calls pl_evaluate. Proof Layer evaluates against your active policy pack and returns a verdict plus a signed receipt. The assistant proceeds only when the verdict is EXECUTE.

Verification

Receipts are independently verifiable using only Ed25519 standard library calls and the public key at https://prooflayer.world999labs.com/v1/public-key. No SDK or account required. For the dependency-free verifier:

npm install @proof-layer/verify

See the main Proof Layer repo for the full verification protocol and offline tooling.

Migrating from @veridocs/mcp

If you're already running @veridocs/mcp@1.2.x, migration is a one-line config change:

Before:

{
  "mcpServers": {
    "veridocs": {
      "command": "npx",
      "args": ["-y", "@veridocs/mcp"],
      "env": {
        "VERIDOCS_API_KEY": "vd_live_..."
      }
    }
  }
}

After:

{
  "mcpServers": {
    "proof-layer": {
      "command": "npx",
      "args": ["-y", "@proof-layer/mcp"],
      "env": {
        "PROOF_LAYER_API_KEY": "vd_live_..."
      }
    }
  }
}

Your existing vd_live_... API key continues to work — only the env variable name changed. Tool names changed from vd_* to pl_* but they're discovered dynamically by the MCP host, so no further config edits are required.

The @veridocs/mcp package remains installable via npm but is deprecated and will not receive new features. Critical security fixes will be backported through 2026-Q3.

License

MIT — © WORLD999_LABS

Built by Proof Layer.