macOS Defaults MCP Server

Instructions

Implementation Reference

• src/mcp_server_macos_defaults/server.py:172-184 (handler)

  The handler function that executes the 'defaults-read' tool logic by running the macOS 'defaults read' command with the provided domain and optional key, capturing and formatting the output.

  def defaults_read(arguments: dict | None) -> list[types.TextContent]:
      if arguments is None:
          return []
      domain = arguments["domain"]
      key = arguments.get("key")
  
      if key is None:
          result = subprocess.run(["defaults", "read", domain], capture_output=True)
          return [types.TextContent(type="text", text=result.stdout.decode("utf-8"))]
  
      result = subprocess.run(["defaults", "read", domain, key], capture_output=True)
      value = result.stdout.decode("utf-8").strip()
      return [types.TextContent(type="text", text=f"{key}: {value}")]

• src/mcp_server_macos_defaults/server.py:126-143 (registration)

  Registers the 'defaults-read' tool in the list_tools handler, specifying its name, description, and input schema (domain required, key optional).

  types.Tool(
      name="defaults-read",
      description = "use the `defaults read <domain> <key>` command",
      inputSchema = {
          "type": "object",
          "properties": {
              "domain": {
                  "type": "string",
                  "description": "Domain to read from",
              },
              "key": {
                  "type": "string",
                  "description": "Key to read from",
              },
          },
          "required": ["domain"],
      },
  ),

• src/mcp_server_macos_defaults/server.py:129-142 (schema)

  JSON schema for the 'defaults-read' tool inputs, defining properties for 'domain' (required) and 'key' (optional).

  inputSchema = {
      "type": "object",
      "properties": {
          "domain": {
              "type": "string",
              "description": "Domain to read from",
          },
          "key": {
              "type": "string",
              "description": "Key to read from",
          },
      },
      "required": ["domain"],
  },

• src/mcp_server_macos_defaults/server.py:222-223 (helper)

  Dispatch logic in the main call_tool handler that routes 'defaults-read' calls to the defaults_read function.

  elif name == "defaults-read":
      return defaults_read(arguments)