AbletonMCP

Implementation Reference

• MCP_Server/server.py:253-262 (handler)

  The handler function for the 'get_session_info' MCP tool. It is registered via the @mcp.tool() decorator and proxies the command to the Ableton Remote Script via socket connection, returning the session information as formatted JSON.

  @mcp.tool()
  def get_session_info(ctx: Context) -> str:
      try:
          ableton = get_ableton_connection()
          result = ableton.send_command("get_session_info")
          return json.dumps(result, indent=2)
      except Exception as e:
          logger.error(f"Error getting session info: {str(e)}")
          return f"Error getting session info: {str(e)}"

• MCP_Server/server.py:253-262 (registration)

  The @mcp.tool() decorator registers this function as the MCP tool named 'get_session_info'.

  @mcp.tool()
  def get_session_info(ctx: Context) -> str:
      try:
          ableton = get_ableton_connection()
          result = ableton.send_command("get_session_info")
          return json.dumps(result, indent=2)
      except Exception as e:
          logger.error(f"Error getting session info: {str(e)}")
          return f"Error getting session info: {str(e)}"

• MCP_Server/server.py:93-93 (helper)

  The send_command method of AbletonConnection class, used by the tool to send the 'get_session_info' command to the Ableton Remote Script.

  def send_command(self, command_type: str, params: Dict[str, Any] = None) -> Dict[str, Any]:

• MCP_Server/server.py:196-249 (helper)

  Helper function to get or establish a connection to Ableton, which uses 'get_session_info' for validation and is called by the tool handler.

  def get_ableton_connection():
      """Get or create a persistent Ableton connection"""
      global _ableton_connection
  
      if _ableton_connection is not None:
          try:
              # quick liveness test (non-intrusive)
              _ableton_connection.sock.settimeout(0.5)
              _ableton_connection.sock.send(b'')  # may raise if broken
              _ableton_connection.sock.settimeout(None)
              return _ableton_connection
          except Exception as e:
              logger.warning(f"Existing connection is no longer valid: {str(e)}")
              try:
                  _ableton_connection.disconnect()
              except Exception:
                  pass
              _ableton_connection = None
  
      # Try to establish a new persistent connection (retries)
      max_attempts = 3
      for attempt in range(1, max_attempts + 1):
          try:
              logger.info(f"Connecting to Ableton (attempt {attempt}/{max_attempts})...")
              candidate = AbletonConnection(host="localhost", port=9877)
              if candidate.connect():
                  _ableton_connection = candidate
                  # basic validation
                  try:
                      _ableton_connection.send_command("get_session_info")
                      logger.info("Connection validated successfully")
                      return _ableton_connection
                  except Exception as e:
                      logger.error(f"Connection validation failed: {str(e)}")
                      _ableton_connection.disconnect()
                      _ableton_connection = None
              else:
                  _ableton_connection = None
          except Exception as e:
              logger.error(f"Connection attempt {attempt} failed: {str(e)}")
              if _ableton_connection:
                  try:
                      _ableton_connection.disconnect()
                  except Exception:
                      pass
                  _ableton_connection = None
  
          if attempt < max_attempts:
              import time
              time.sleep(1.0)
  
      logger.error("Failed to connect to Ableton after multiple attempts")
      raise Exception("Could not connect to Ableton. Make sure the Remote Script is running and Ableton is open.")