Wire NCI into Cursor

Add the MCP server

Edit ~/.cursor/mcp.json, or open CursorSettingsMCP:

{
  "mcpServers": {
    "nci": {
      "command": "npx",
      "args": ["-y", "@nativecontextindex/mcp"],
      "env": {
        "NCI_PROJECT_ROOT": "${workspaceFolder}"
      }
    }
  }
}

Cursor expands ${workspaceFolder} in env when it loads mcp.json (config interpolation). That becomes NCI_PROJECT_ROOT inside nci-mcp, which passes global nci -r on every tool call — required for active_package when the server is registered in global ~/.cursor/mcp.json (where MCP cwd is often not the repo).

If nci is not on Cursor’s PATH, add NCI_BINARY too:

{
  "mcpServers": {
    "nci": {
      "command": "npx",
      "args": ["-y", "@nativecontextindex/mcp"],
      "env": {
        "NCI_PROJECT_ROOT": "${workspaceFolder}",
        "NCI_BINARY": "/absolute/path/to/nci"
      }
    }
  }
}

Find the absolute path with:

Apply changes

Cursor watches mcp.json and rebuilds the server list when you save — no app restart needed. Open CursorSettingsMCP to confirm nci is listed with two tools and three resources. If the toggle row looks stuck, the command palette’s Developer: Reload Window is the only escalation you should ever need.

Best-practice prompts

• “Look up ZodObject.omit in the version of zod we have installed before writing the schema.”
• “List the public exports of @my-org/shared so I can decide what to import.”
• “Find every overload of useState and tell me which packages provide it.”

The agent picks the right nci_query subcommand. Pin package_name and package_version in the prompt when you want exact answers fast — the agent primer goes into more detail on why.

Re-index on demand

NCI’s tools read the database; they do not build it. Re-run nci index whenever the lockfile changes:

For monorepo setups see Monorepo indexing.

Troubleshooting

If Cursor reports the wrong NCI version or “binary not found”, set NCI_BINARY to the path printed by nci binary-path. The Node shim and nci-mcp both defer to it.

Skills

Cursor follows the open Agent Skills standard. NCI’s shipped skill (nci-answer-quality) drops into Cursor’s discovery path with no rewriting — see NCI Skills for the host-by-host map.