FlexSim MCP Server

Instructions

Args:
    node_path: Path to node (e.g., "Model/Queue1/stats/input")

Implementation Reference

• mcp_server/flexsim_mcp.py:386-400 (handler)

  Main handler implementation for flexsim_get_node_value tool. Uses the @mcp.tool() decorator for registration, takes NodeAccessInput parameters, and retrieves values from FlexSim tree nodes using FlexScript's getvalue() function.

  @mcp.tool()
  async def flexsim_get_node_value(params: NodeAccessInput) -> str:
      """Get value from FlexSim tree node.
  
      Args:
          node_path: Path to node (e.g., "Model/Queue1/stats/input")
      """
      try:
          controller = await get_controller()
          script = f'getvalue(node("{params.node_path}"))'
          result = controller.evaluate(script)
  
          return f"{params.node_path} = {result}"
      except Exception as e:
          return format_error(e)

• mcp_server/flexsim_mcp.py:93-96 (schema)

  Schema definition for NodeAccessInput which defines the input parameters for flexsim_get_node_value tool. Uses Pydantic BaseModel for validation with a required node_path field.

  class NodeAccessInput(BaseModel):
      """Input for node operations."""
      node_path: str = Field(..., min_length=1)
      value: Any | None = Field(default=None)

• mcp_server/flexsim_mcp.py:129-140 (helper)

  Helper function that formats exceptions into user-friendly error messages. Used by flexsim_get_node_value to handle errors gracefully.

  def format_error(e: Exception) -> str:
      """Format exception as user-friendly error message."""
      msg = str(e)
      if "not found" in msg.lower():
          return f"Not found: {msg}"
      elif "syntax" in msg.lower():
          return f"FlexScript syntax error: {msg}"
      elif "license" in msg.lower():
          return f"License error: {msg}"
      elif "permission" in msg.lower():
          return f"Permission denied: {msg}"
      return f"Error: {msg}"

• mcp_server/flexsim_mcp.py:147-154 (helper)

  Helper function that gets or creates the FlexSim controller instance. Used by flexsim_get_node_value to obtain the controller for executing FlexScript commands.

  async def get_controller():
      """Get or create the FlexSim controller instance."""
      global _controller
  
      async with _controller_lock:
          if _controller is None:
              _controller = await launch_flexsim()
          return _controller