RelayOrb

Claude Desktop MCP servers: the config file, and how to see every call

Updated

Claude Desktop loads MCP servers from claude_desktop_config.json. This guide shows where that file is, what goes in it, and how to record every tool call Claude makes.

Where the config file is

You can also open it from Claude Desktop's settings, in the Developer section. Restart Claude Desktop after editing it.

  • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
  • Windows: %APPDATA%\Claude\claude_desktop_config.json

Add a server, recorded by RelayOrb

Use the absolute path to relayorb as the command, because Claude Desktop doesn't load your shell's PATH. Everything after -- is the original server command.

claude_desktop_config.json

{
  "mcpServers": {
    "fs": {
      "command": "/Users/you/.local/bin/relayorb",
      "args": ["record", "--name", "desktop-fs", "--", "npx", "-y", "@modelcontextprotocol/server-filesystem", "/Users/you/notes"]
    }
  }
}

See what Claude did

After a conversation, run relayorb show desktop-fs to get the timeline of tool calls, or relayorb show desktop-fs --json for the complete requests and responses. Claude Desktop's own MCP logs show server output, while RelayOrb shows the protocol messages themselves.

Terminal

relayorb show desktop-fs

Install RelayOrb

Free and open source (Apache-2.0). A single binary for macOS, Linux, and Windows. No account, no cloud, no telemetry.

macOS / Linux

curl -fsSL https://relayorb.com/install.sh | sh

Windows and other options: GitHub Releases.

FAQ

Where is claude_desktop_config.json?
On macOS: ~/Library/Application Support/Claude/claude_desktop_config.json. On Windows: %APPDATA%\Claude\claude_desktop_config.json.
Why isn't my MCP server showing up in Claude Desktop?
Check that the JSON is valid, that the command is an absolute path, and that you fully restarted Claude Desktop.