msfs2024-mcp

A Model Context Protocol server for Microsoft Flight Simulator 2024. It lets an MCP client (Claude Desktop, Claude Code, etc.) read live sim state and drive the aircraft across three capability layers:

Reality check: SimConnect, FSUIPC, and raw memory are Windows-only and require a running MSFS on the same machine (or LAN via SimConnect.cfg). Run this server on that Windows host. Every layer degrades gracefully — if a layer isn't available, its tools return a structured { "ok": false, "error": ... } explaining why, instead of crashing the server. So the server boots and the catalog/discovery tools work even before MSFS is up.

Install (on the Windows host with MSFS)

git clone <your-repo-url> msfs2024-mcp
cd msfs2024-mcp
python -m venv .venv
.venv\Scripts\activate
pip install -e .
copy .env.example .env   # then edit if you like

Layer prerequisites:

• SimConnect — installed automatically with the SimConnect pip package, which ships its own SimConnect.dll. Just have MSFS running and loaded into a flight.

• FSUIPC7 — download and run FSUIPC7 (free for basic offset access). Leave it running alongside MSFS.

• Raw memory — set MSFS_ENABLE_MEMORY=true in .env and run the server as Administrator. Off by default.

Related MCP server: MSFS SDK MCP Server

Verify it works

python scripts\smoke_test.py

With MSFS loaded into a flight you'll see a live aircraft-state snapshot and an event round-trip (nav lights toggle). Off-Windows or with the sim closed, it prints layer health and exits cleanly — which is how you know the graceful-degradation path is intact.

Platform-independent tests (catalog integrity + degradation) run anywhere:

pip install -e ".[dev]"
pytest -q

Wire into an MCP client

Claude Desktop / Claude Code — add to your MCP config (claude_desktop_config.json or .mcp.json):

{
  "mcpServers": {
    "msfs2024": {
      "command": "python",
      "args": ["-m", "msfs_mcp.server"],
      "cwd": "C:\\path\\to\\msfs2024-mcp",
      "env": { "MSFS_ENABLE_FSUIPC": "true", "MSFS_ENABLE_MEMORY": "false" }
    }
  }
}

(If you pip install -e ., you can use the msfs-mcp console script instead of python -m msfs_mcp.server.)

Tool surface (23 tools)

Connection — connection_status, connect_sim

SimConnect / SimVars — get_simvar, get_simvars, set_simvar, get_aircraft_state

SimConnect / Events & autopilot — trigger_event, autopilot_set_heading, autopilot_set_altitude, autopilot_set_vertical_speed, autopilot_toggle_master

Discovery — list_simvars, list_events (searchable by keyword/category)

FSUIPC — fsuipc_status, fsuipc_read_offset, fsuipc_read_known, fsuipc_write_offset

Raw memory — memory_status, memory_attach, memory_module_base, memory_read, memory_read_pointer_chain, memory_write

Resources — msfs://telemetry/state, msfs://catalog/simvars, msfs://catalog/events

Prompts — preflight_briefing, fly_to_heading_altitude

Examples (natural language to the MCP client)

• "What's my current altitude and heading?" → get_aircraft_state

• "Find me every autopilot-related variable." → list_simvars(category="autopilot")

• "Raise the landing gear and set flaps to the first notch." → trigger_event('GEAR_UP'), trigger_event('FLAPS_INCR')

• "Engage the autopilot for heading 270 at 8000 feet." → autopilot_toggle_master, autopilot_set_heading(270), autopilot_set_altitude(8000)

• "Read FSUIPC offset 0x0560 as a long." → fsuipc_read_offset('0x0560', 'l')

Safety notes

• Writes are real. set_simvar, trigger_event, and fsuipc_write_offset change the running sim. Fine for your own local flight; think before scripting them.

• Raw memory is double-gated. It requires both MSFS_ENABLE_MEMORY=true and allow_write=true per write call, because bad writes can crash MSFS. Pointer chains break on most sim updates — keep them version-pinned.

• Reads are harmless. All read paths are observation-only.

Extending the catalog

src/msfs_mcp/catalog.py is a curated subset, not the full SDK. The generic get_simvar / set_simvar / trigger_event tools reach any SimVar or Event by exact SDK name — add entries to the catalog only to make them discoverable. Full reference: the MSFS SDK SimVars and Event IDs docs.

Architecture

MCP client  ──stdio──▶  msfs_mcp.server (FastMCP, 23 tools)
                              │
              ┌───────────────┼────────────────┐
              ▼               ▼                 ▼
     SimConnectClient   FsuipcClient      MemoryClient
     (SimConnect.dll)   (FSUIPC7)         (pymem)
              │               │                 │
              └──────── Microsoft Flight Simulator 2024 ────────┘

Each client is a singleton with lazy connect, a thread lock around the native handle, and a uniform LayerUnavailable error contract that the server renders as structured JSON.

License

MIT

Companion apps

• EFB Checklist — PyQt6 always-on-top electronic checklist (normal + emergency procedures, V-speeds) for flying alongside MSFS 2024. Ships with the Cessna 172S and Piper PA-28-181 Archer.