Local MCP
Some data should never go to a cloud MCP server. Local stdio keeps files on disk and latency near zero.
Local MCP is a home workshop. The tools are on your bench. Nothing is shipped to a warehouse.
Visual Workflows
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Overview
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How Cursor attaches a local server
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The host owns the child process. If the process dies, reconnect or restart the host.
Key Takeaways
- 1.Local MCP runs on your machine as a child process over stdio. The client starts a command from mcp.json and talks on stdin/stdout.
- 2.Best for source code, .env files, and local databases that must not leave. No OAuth needed — your OS user permissions are the security boundary.
- 3.stdio means one JSON-RPC message per line. Logs belong on stderr.
- 4.Point filesystem servers at a project folder, never the whole home directory, unless you truly mean that.
Learn elsewhere
- →Remote HTTP servers — next module
- →OAuth — Authentication
Real Example
Scenario
Cursor spawns @modelcontextprotocol/server-filesystem on your repo root. The agent can read and write project files without a network round trip.
What you would do
In Model Context Protocol, apply Local MCP to this scenario: Cursor spawns @modelcontextprotocol/server-filesystem on your repo root. Identify the inputs, run the technique, validate the output, and note one thing you would monitor in production.
Commands
Commands to Remember
npx -y @modelcontextprotocol/server-filesystem <folder>Logs go to stderr, never stdoutScope the directory tightlystdio = local child process
Cheat Sheet
Quick recap
quick ref- •Local = stdio child process
- •Configured in mcp.json
- •Great for files and local DBs
- •OS permissions are your auth
Common Mistakes
- ✕Pointing the filesystem server at the entire disk
- ✕console.log on stdout breaking JSON-RPC
- ✕Assuming local MCP is reachable from another computer