Connect MCP in Cursor

Give Cursor agents offline schema diff tools and hosted watch access — one MCP server, no polling until you add an API key.

Prerequisites: Node.js 20+, the DriftGuard OSS repo built locally (npm ci && npm run build), and optionally a hosted API key from /activate.

What you will configure

1. Build the MCP server

   Compile TypeScript so dist/mcp/server.js exists.

2. Add DriftGuard to Cursor MCP settings

   Point Cursor at the local server entry with absolute paths.

3. Verify offline tools

   Run compare_json and parse_mcp_config without network.

4. Enable hosted tools (optional)

   Set DRIFTGUARD_API_KEY for watches, drift explain, and coverage.

Step 1 — Build the MCP server

Clone and build once per machine. The MCP server runs on stdio — Cursor spawns it as a child process.

git clone https://github.com/kioie/driftguard.git
cd driftguard && npm ci && npm run build
# Entry point: $(pwd)/dist/mcp/server.js

Step 2 — Open Cursor MCP settings

In Cursor, open SettingsMCP and edit your user or project mcp.json. Add a driftguard server block:

{
  "mcpServers": {
    "driftguard": {
      "command": "node",
      "args": ["/absolute/path/to/driftguard/dist/mcp/server.js"],
      "env": {
        "DRIFTGUARD_API_KEY": "dg_live_…"
      }
    }
  }
}

Omit DRIFTGUARD_API_KEY for offline-only mode. Use an absolute path — tilde expansion is not reliable across MCP clients.

Step 3 — Verify offline tools

Ask the agent to diff two JSON blobs or parse an mcp.json snippet. These tools work without network:

• compare_json — breaking / warning / info classification
• parse_mcp_config — preview URLs from a local MCP config

In Cursor chat, try: “Use compare_json on these two OpenAPI fragments and list breaking changes.”

Step 4 — Add hosted tools

Copy your API key from ConsoleAccountAPI keys or /activate. Restart Cursor after updating mcp.json.

Hosted tools (require key): list_watches, get_watch_status, explain_drift, assert_coverage. Missing key returns a clear trial/pricing message — never a silent failure.

Walkthrough video

Next steps

• Set up your first watch
• MockDrift agent replay
• MCP client matrix (OSS)