Mix a Behringer XR18 from an assistant

What it does

xr18-mcp is an MCP server for a Behringer XR18. The README says mixer commands go out as OSC on UDP port 10024. The command list is built from a parameters file in the repo, a supplied X AIR OSC protocol PDF, and the Behringer World X-Air OSC reference. Raw tools cover documented paths that do not have their own named tool, including paths that depend on firmware.

The mixing tools speak dB. xr18_list_channels and xr18_resolve_channel cover regular channels, the AUX return, FX returns, monitor buses, FX sends, LR, and DCAs. Fader tools get, set, and nudge a level. Send tools do the same for a bus. Sends 1 through 6 are the monitor buses. Sends 7 through 10 are FX sends 1 through 4. A destination can be a bus number, a name you configured, or an id such as bus/5 or fxsend/2. The README says fxsend/2 maps to channel send slot 08. Other ids it lists are ch/10, rtn/aux, rtn/1, lr, and dca/1.

Lower-level tools read mixer info and status, turn on /xremote, get or set a raw path, fire a trigger, list and describe commands, and read meter batches 0 through 9 in dB. Separate tools set a channel fader or mute, set headamp phantom, and load, save, delete, or scope a snapshot. The README says to call xr18_describe_command before writing a raw path you have not used. Native float values on the desk run from 0.0 to 1.0.

Writes do not wait for an echo. The README says XR18 firmware does not reliably echo set messages, so a write is fire-and-forget, while a query still waits for a reply. The absolute setters take verify=true, which sends the value and then reads it back. A relative change reads the current dB, sends the new value without waiting, and returns the dB it expects. confirm=true is required before console initialization, applying network settings, deleting a snapshot, or changing phantom power. The README says a network update can drop the server off the mixer, and that the XR18 ignores /-action/setclock. /xremote subscriptions expire after ten seconds, so xr18_enable_remote has to be called again while you are listening for changes.

The repo also includes a Google ADK mixer assistant that runs against a local llama.cpp server and accepts English and Italian. The README says that agent is limited to nine tools, that gain math stays in Python, and that the agent cannot enable phantom, initialize the console, delete snapshots, or change network settings. Ambiguous strip names are rejected.

How to set it up

1. Install Python 3.12 or newer and uv. Clone the repo, run uv sync, and set XR18_HOST to the mixer. XR18_PORT defaults to 10024. XR18_TIMEOUT defaults to 2 seconds.
2. Start it with uv run xr18-mcp. For a client config, the README uses uv run --directory with the repo path and passes XR18_HOST in env.
3. Ask for a channel list before the first move. Pass verify=true on xr18_set_fader_db or xr18_set_send_db when you need a readback.
4. Leave phantom, snapshot deletion, console initialization, and network changes alone unless you pass confirm=true and you are on a desk you can reset.
5. The optional local agent needs llama-server --jinja and a model with a tool-calling template. Copy agents/.env.example to agents/.env, set the host, then from agents run uv run adk run mixer_assistant.

Source project: gdeber/xr18-mcp

FAQ

Does a fader move get confirmed by the desk?

A normal write does not wait for an echo. The README says the firmware does not reliably echo sets. Pass verify=true on the absolute dB setters when you want a separate read after the write.

Can the assistant turn phantom on?

The MCP server can, and only with confirm=true. The README's local ADK agent is a narrower surface: it cannot enable phantom, initialize the console, delete snapshots, or change network settings.