MCP Policy Gatekeeper

Instructions

Implementation Reference

• server.py:170-177 (handler)

  The handler for the 'read_file' tool. Resolves the path using resolve_path, checks if the file exists, reads the content if it does, and returns it wrapped in TextContent. Errors if not found.

  elif name == "read_file":
      path = resolve_path(arguments["path"])
      if not path.exists():
          return [TextContent(type="text", text=f"Error: File '{arguments['path']}' not found")]
      
      with open(path, 'r', encoding='utf-8') as f:
          content = f.read()
      return [TextContent(type="text", text=content)]

• server.py:92-98 (schema)

  Input schema definition for the 'read_file' tool, specifying an object with a required 'path' string property.

  inputSchema={
      "type": "object",
      "properties": {
          "path": {"type": "string", "description": "File path"}
      },
      "required": ["path"]
  }

• server.py:89-99 (registration)

  Registration of the 'read_file' tool in the list_tools() function, including name, description, and input schema.

  Tool(
      name="read_file",
      description="Read contents of a file",
      inputSchema={
          "type": "object",
          "properties": {
              "path": {"type": "string", "description": "File path"}
          },
          "required": ["path"]
      }
  ),