MCP Servers Are Untrusted Code

Tip: Treat MCP like a plugin with a permission boundary

An MCP server can expose tools that read files or hit the network. Pin versions, review the tool list, and run untrusted servers in a sandbox.

{
  "mcpServers": {
    "docs": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "./docs"]
    }
  }
}

Gotcha: A filesystem MCP with / is a data leak

Never point a filesystem server at $HOME or /. Scope the root to the repo or a scratch dir.

{"args": ["-y", "@modelcontextprotocol/server-filesystem", "/"]}

Source: https://modelcontextprotocol.io/docs/concepts/architecture