Nobody Asks Where MCP Servers Get Their Data

Fazm Team··2 min read

Nobody Asks Where MCP Servers Get Their Data

MCP (Model Context Protocol) is becoming the standard way AI agents interact with tools and data sources. You install an MCP server, connect your agent, and suddenly it can read your files, query your databases, or control your browser. Powerful stuff. But almost nobody asks the obvious question: who controls what the server can access?

The Trust Surface

When you install an MCP server, you are granting it a trust surface - the set of systems and data it can reach. Most MCP servers run with your user permissions. That means they can access everything you can access.

Think about what that includes: your SSH keys, your browser cookies, your API tokens stored in environment variables, every file on your machine. The MCP server is a bridge between an AI model and your entire digital life.

The Questions Nobody Asks

  • Who wrote this MCP server? Have you read the source code?
  • Does the server phone home? Does it send telemetry that includes your data?
  • What happens when the server gets an update? Do new permissions get added silently?
  • If the AI agent sends a malicious prompt to the MCP server, what is the blast radius?

Open Source Helps but Does Not Solve

Open source MCP servers are better because you can audit the code. But most people do not audit it. They install, configure, and forget. Meanwhile the server sits between their AI agent and their operating system with full access to both.

What to Do About It

Run MCP servers with minimal permissions. Use separate user accounts or containers when possible. Prefer MCP servers that declare their permission scope explicitly. And when an MCP server asks for access to your entire file system to provide a simple tool, ask why.

The MCP ecosystem is young. The security practices need to catch up to the capabilities.

Fazm is an open source macOS AI agent. Open source on GitHub.

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