FlexSim MCP Server

Instructions

Implementation Reference

• mcp_server/flexsim_mcp.py:268-312 (handler)

  Main implementation of flexsim_run_to_time tool. Handles both fast mode (blocking, no GUI) and real-time mode (with GUI updates) simulation running until a target time is reached.
  @mcp.tool() async def flexsim_run_to_time(params: RunToTimeInput) -> str: """Run simulation until reaching target time. Args: target_time: Target simulation time in seconds fast_mode: Run at maximum speed (default: True). Set to False for real-time GUI updates. Example: target_time=3600 # Run for 1 hour """ try: controller = await get_controller() start = controller.time() if start >= params.target_time: return f"Already at time {format_time(start)}" if params.fast_mode: # Fast mode: blocking call at max speed (no GUI updates) controller.runToTime(params.target_time) else: # Real-time mode: set stop time and run with GUI animation controller.evaluate(f"setstoptime({params.target_time})") controller.run() # Poll until target time reached or simulation stops while True: current = controller.time() if current >= params.target_time: controller.stop() break await asyncio.sleep(0.1) end = controller.time() mode_str = "fast" if params.fast_mode else "real-time" return ( f"✓ Simulation complete ({mode_str})\n" f"Start: {format_time(start)}\n" f"End: {format_time(end)}\n" f"Duration: {format_time(end - start)}" ) except Exception as e: return format_error(e)
• mcp_server/flexsim_mcp.py:82-86 (schema)

  Pydantic BaseModel schema defining input parameters for flexsim_run_to_time tool. Validates target_time (must be positive) and fast_mode (optional, defaults to False).
  class RunToTimeInput(BaseModel): """Input for running to a specific time.""" target_time: float = Field(..., gt=0) fast_mode: bool = Field(default=False)
• mcp_server/flexsim_mcp.py:268-268 (registration)

  Tool registration using FastMCP's @mcp.tool() decorator, which automatically registers flexsim_run_to_time with the MCP server and generates the tool schema from the RunToTimeInput type hint.
  @mcp.tool()
• mcp_server/flexsim_mcp.py:119-126 (helper)

  Helper function used by flexsim_run_to_time to format simulation time values (seconds) into human-readable strings (s/m/h).
  def format_time(seconds: float) -> str: """Format simulation time as human-readable string.""" if seconds < 60: return f"{seconds:.2f}s" elif seconds < 3600: return f"{seconds/60:.2f}m" else: return f"{seconds/3600:.2f}h"
• mcp_server/flexsim_mcp.py:147-154 (helper)

  Helper function that lazily initializes and returns the FlexSim controller instance. Used by flexsim_run_to_time to access the FlexSim API.
  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