source2mcp

An MCP server that drives Source 2 games (CS2, Deadlock, Dota 2, Half-Life: Alyx, SteamVR Home, Aperture Desk Job and Aperture Robot Repair) through VConsole2, the console protocol of the engine. It injects no code into the game.

Run

You need Windows, the .NET SDK and the game installed through Steam.

dotnet run --project src -- --port 13339

The default port is 13339. Add the server to Claude Code:

claude mcp add --transport http source2mcp http://127.0.0.1:13339/mcp

Tools

Tool	What it does
launch	Starts the game, loads a map and runs the setup. With tools, it starts the game in tools mode. With compare, it prepares repeatable screenshots.
map	Loads a map and waits until the player is in the game. With addon, it loads the map from an addon or a workshop item. Takes compare as launch does.
console	Runs console commands and returns their output, the unknown commands, and the cvars that did not get the requested value.
camera	Moves the camera and reads it back with getpos. In Dota 2, it only reads the camera.
screenshot	Saves what the game renders to a PNG file, a few frames after the earlier commands.
cvars	Finds cvars and commands, and marks hidden ones. Half-Life: Alyx, SteamVR Home and the Aperture games send no values or help text.
restore_cvars	Sets the cvars that the server changed back to their original values.
get_log	Returns recent log lines.
get_status	Reports the process, the connection and the changed cvars. After the game exits, it gives the exit code and the last log lines.
quit	Restores the changed cvars and stops the game.

Safety

• The game always starts with -insecure and sv_cheats 1. SteamVR Home allows sv_cheats only in tools mode, so it always starts with -tools.
• The server loads maps from the game, its local addons and subscribed workshop items, and checks that the map exists first. console refuses connect, quit and the commands that load maps (map, changelevel, map_workshop, dota_launch_custom_game, addon_play and destinations_load_addon).
• The server does not change game files. The game runs with the user's config and saves archived cvars to it on quit. Thus the server records the value of each cvar before it first changes it, through console, launch or map, and quit sets it back. The reply of quit lists the cvars that could not be restored. In Half-Life: Alyx, map with addon enables the addon, and quit sets default_enabled_addons_list back.
• launch sets engine_no_focus_sleep 0 through the console, so that the game renders at full rate without focus, and quit restores it. A +cvar launch argument is saved to the config like a console change, so the server does not set archived cvars on the command line.

Addon maps

Game	addon	Command
CS2	Workshop item id	map_workshop
Dota 2	Folder in dota_addons	dota_launch_custom_game
Half-Life: Alyx	Folder in hlvr_addons or workshop item id	addon_enable and addon_play
SteamVR Home	Folder in steamtours_addons or workshop item id	destinations_load_addon

All SteamVR Home maps are in addons, for example Supervillain Lair in workshop item 1449138879.

Repeatable screenshots

Give compare to launch or map. It runs these steps and returns the value of each cvar:

1. Run noclip until it reports on, except in Dota 2 and Aperture Desk Job, which have no noclip.
2. Run cl_drawhud 0, r_drawviewmodel 0 and r_drawpanorama 0, and r_always_render_all_windows 1 and r_vconsole_foregroundforcerender 1 where the game shows them.
3. With exposure, set mat_tonemap_force_min and mat_tonemap_force_max to it. Deadlock and Dota 2 ignore these cvars.
4. With host_framerate, set host_framerate. Do not set host_timescale 0.

Use with vrf

The server uses the same position, angle and FOV conventions as the vrf server of Source 2 Viewer. To compare a frame:

1. Open de_dust2 in Source 2 Viewer, and launch CS2 with de_dust2.
2. Give the same position, angles and fov to camera in the two servers.
3. Take a screenshot in each, then use vrf.compare_screenshots.