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MCP Playground

May 18, 2025
Tech AI

Notes about findings and understandings around Model Context Protocol aka _MCP.

Questions

Open questions that I have.

  • Can I run Claude with different MCP Server configurations? I.e. I have one configuration per project, say one for my Python project (including access only to my Python project directory), one for my Swift/Xcode project (with a different dir and different tools).
  • Test: Play around with MCP Inspector and Xcode Build MCP Server.

Accessing a MCP server

When searching and eventually finding an MCP server for my use case, I find it helpful to play around with them, in order to understand what tooling the LLM gets. The easiest way to do this is with the MCP Inspector.

Get going:

# Make sure you have installed a recent version of nodeJs (in my case with nvm)
nvm use 24
npx @modelcontextprotocol/inspector node build/index.js

# It downloads & starts the MCP UI Client and serves it locally.

Configuration

The Inspector keeps whatever you type in the sidebar in localStorage, but for repeatable setups you can save a tiny JSON file and point the CLI to it:

// mcp.json
{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/Users/yourname/Projects", // read/write
        "/Users/yourname/Notes", // read/write
        "/Users/yourname/Code" // read-only? add ',ro' if you use Docker
      ]
    }
  }
}

Then run npx @modelcontextprotocol/inspector --config ./mcp.json --server filesystem

MCP Servers

MCP Servers I used or looked at:

Filesystem MCP Server

Main config:

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/Users/username/Desktop",
        "/path/to/other/allowed/dir"
      ]
    }
  }
}

MCP Servers

MCP Servers I tested or plan to test.

FileSystem Access

Xcode Build

Xcode Build

  • Enables Xcode build actions.
  • https://github.com/cameroncooke/XcodeBuildMCP