Install and connect

Build the SITL binary

mcardupilot runs a SITL binary you have already built. It never builds or edits the ArduPilot tree. By default it looks for the tree in ~/ardupilot, where ArduPilot’s setup guide clones it, and runs build/sitl/bin/arduplane from there.

cd ~/ardupilot
./waf configure --board sitl
./waf plane

A tree elsewhere, or a binary outside a tree:

export MCARDUPILOT_ARDUPILOT=/path/to/ardupilot
export MCARDUPILOT_BINARY=/path/to/arduplane     # only if it is not <tree>/build/sitl/bin/arduplane

With a binary outside <tree>/build/<board>/bin/, the server cannot find the frame’s default parameter files, so pass params=[...] to open_sitl yourself.

Add the server

From PyPI

mcardupilot is on PyPI, so uvx fetches and runs it:

claude mcp add mcardupilot -- uvx mcardupilot

Add --refresh to the uvx arguments if you want each start to pick up a newer release.

From a checkout

claude mcp add mcardupilot -- uv run --directory /path/to/mcardupilot mcardupilot

uv run --directory runs the editable install, so restarting the server picks up every edit to the source.

Other clients

The server speaks MCP over stdio by default. Any client that launches a command works:

{
  "mcpServers": {
    "mcardupilot": {
      "command": "uv",
      "args": ["run", "--directory", "/path/to/mcardupilot", "mcardupilot"],
      "env": { "MCARDUPILOT_ARDUPILOT": "/path/to/ardupilot" }
    }
  }
}

On start the server prints one line to stderr, never stdout, which belongs to the protocol:

mcardupilot v2026.10.03 ardupilot=~/ardupilot pool=40-59 data=~/.local/share/mcardupilot transport=stdio

If the binary is missing it says so on the next line, and keeps running so server_info can tell you the same.

Check it

Ask your agent for server_info:

{
  "version": "2026.10.3",
  "binary_exists": true,
  "binary_mtime": "2026-10-02T18:30:12+00:00",
  "instance_pool": "40-59",
  "leases_held": {},
  "reconciled": [],
  "wait_cap_s": 85.0,
  "log_budget_gb": 20.0,
  "logs_used_gb": 0.0
}

binary_exists: true means sessions can start. leases_held lists every instance someone holds, from any process sharing the data directory. reconciled lists SITLs a dead server left behind that this one killed at start.

Several agents, one machine

Every agent session runs its own server process. They coordinate only through the shared data directory, so give them all the same MCARDUPILOT_DATA_DIR (the default already is). Why that is enough.

Run over HTTP

For a client that cannot launch a process:

MCARDUPILOT_TRANSPORT=http MCARDUPILOT_HTTP_PORT=8374 uv run --directory /path/to/mcardupilot mcardupilot

The server listens on 127.0.0.1 by default and has no authentication of its own. Over HTTP it reads logs only from under its data directory.