MCP Chat

Instructions

Implementation Reference

• mcp_chat/server.py:33-146 (handler)

  The handler function for the 'join_room' tool. It creates a unique client_id, joins or creates a chat room (max 2 users), notifies existing user if joining as second, and returns status with client_id.
  @mcp.tool() async def join_room(room_id: str, display_name: str) -> Dict[str, Any]: """Join a specific chat room directly. Creates a new session with a unique client_id and adds the user to the specified room. Useful for rejoining a room or creating private rooms. IMPORTANT: After joining a room, prompt the user to choose whether they want to: - Wait for messages (call wait_for_message) - if they expect to receive first - Send a message (call send_message) - if they want to initiate conversation This gives users control over the conversation flow rather than automatically blocking. Args: room_id: The ID of the room to join display_name: Display name for the user (required) Returns: Success status with client_id or error information """ # Generate a unique client_id for this user connection_id = str(uuid.uuid4()) # Create new user user = User(display_name=display_name, connection_id=connection_id) connections[connection_id] = user # Check if room exists room = await room_manager.get_room(room_id) if not room: # Create a new room with just this user room = await room_manager.create_room(user, user) # Temporarily both users room.room_id = room_id # Override the generated ID # Update the room in manager room_manager._rooms[room_id] = room room_manager._user_to_room[user.user_id] = room_id logger.info(f"Created new room {room_id} for {user.name}") return { "status": "room_created", "room_id": room_id, "client_id": connection_id, "message": "New room created, waiting for another user to join", } # Check if room is active if not room.active: return { "status": "error", "error": "Room is no longer active", "client_id": connection_id, } # Check if room has space (max 2 users) current_users = [] active_user_ids = {u.user_id for u in connections.values()} if room.user1 and room.user1.user_id in active_user_ids: current_users.append(room.user1) if ( room.user2 and room.user2.user_id != room.user1.user_id and room.user2.user_id in active_user_ids ): current_users.append(room.user2) if len(current_users) >= 2: return {"status": "error", "error": "Room is full", "client_id": connection_id} # Add user to room if len(current_users) == 0: # First user in existing room room.user1 = user else: # Second user joining room.user2 = user # Notify the first user first_user = room.user1 if first_user and first_user.user_id in connections: # Send notification about new user joining if ( room_id in message_queues and first_user.user_id in message_queues[room_id] ): join_msg = { "content": f"[System] {user.name} has joined the chat.", "sender_name": "System", "sender_id": "system", "timestamp": datetime.now().isoformat(), "message_id": str(uuid.uuid4()), "system": True, } try: message_queues[room_id][first_user.user_id].put_nowait(join_msg) except (asyncio.QueueFull, RuntimeError) as e: # Queue might be full or closed logger.debug(f"Could not send join notification: {e}") # Update user-to-room mapping room_manager._user_to_room[user.user_id] = room_id logger.info(f"User {user.name} joined room {room_id}") # Get partner info if exists partner = room.get_partner(user.user_id) return { "status": "joined", "room_id": room_id, "client_id": connection_id, "partner": {"display_name": partner.name} if partner else None, "message": "Successfully joined room" + (f" with {partner.name}" if partner else ", waiting for partner"), }
• mcp_chat/server.py:33-33 (registration)

  Registers the join_room function as an MCP tool using the FastMCP @mcp.tool() decorator.
  @mcp.tool()