AI Blindspots

Use MCP Servers

Model Context Protocol servers provide a standard interface for LLMs to interact with their environment. Cursor Agent mode and Claude Code use agents extensively. For example, instead of needing a separate RAG system (e.g., as previously provided by Cursor) to find and feed the model relevant context files, the LLM can instead call an MCP which will let it lookup what files it wants to look at before deciding what to do. Similarly, a model can run tests or build and then immediately work on fixing problems when this occurs. It is clear that Anthropic’s built-in MCP servers are useful, and you should use agent mode when you can.

Epistemic status: this next section is theoretical, I have not attempted it in practice yet.

A further question to ask is whether or not you should be writing your own MCP servers. One of the built-in MCP servers is a shell, so in practice you can turn on YOLO mode in Cursor and add some instructions to your Cursor rules about what commands to run and this actually works reasonably well. But it’s really dangerous! Arbitrary shell commands can do anything, and there are plenty of shell commands in your LLMs pretraining set that will trash your environment. So you are mostly praying that your LLM doesn’t go off the rails some day (or you’re a careful user and audit every command before running them–let’s be real, who’s got time for that).

The alternative is to write an MCP server that exposes the commands that you want your model to have access to (note, this is a bit different from what most people are thinking of when they write MCPs to access various existing platform APIs). In principle, this should make it easier to control what tools actually end up getting called, but as of March 2025 support for this in Cursor is poor. In particular, there is no direct way to have different MCP servers on a per project basis, and the overall direction the ecosystem is going with MCP servers are to provide tools that are universally applicable, rather than the equivalent of npm run as an MCP server.

Examples