MCP Observer Server

Instructions

Implementation Reference

• src/mcp_observer_server/server.py:196-206 (handler)

  The core handler logic for the 'list_watched' tool within the call_tool_handler function. It checks if any paths are watched and returns a formatted list of monitored paths with subscriber counts, or a message if none are monitored.

  elif name == "list_watched":
      if not watched:
          return [
              TextContent(type="text", text="No paths are currently being monitored")
          ]
  
      result_lines = [f"Currently monitoring {len(watched)} paths:"]
      for path, sessions in watched.items():
          result_lines.append(f"- {path} ({len(sessions)} subscribers)")
  
      return [TextContent(type="text", text="\n".join(result_lines))]

• src/mcp_observer_server/server.py:80-88 (registration)

  Registration of the 'list_watched' tool in the @server.list_tools() handler, defining its name, description, and input schema (no required properties).

  Tool(
      name="list_watched",
      description="List all currently monitored paths and their subscriber counts",
      inputSchema={
          "type": "object",
          "properties": {},
          "additionalProperties": False,
      },
  ),

• src/mcp_observer_server/server.py:83-87 (schema)

  Input schema for the 'list_watched' tool, specifying an empty object with no properties and no additional properties allowed.

  inputSchema={
      "type": "object",
      "properties": {},
      "additionalProperties": False,
  },

• src/mcp_observer_server/server.py:24-24 (helper)

  Global dictionary 'watched' that stores the mapping of monitored paths to sets of subscribed ServerSession objects, directly used by the list_watched handler.

  watched: Dict[Path, Set[ServerSession]] = {}