dth-houdini-mcp

An MCP server exposing a live Houdini session for inspecting and debugging the DazToHue (DTH) pipeline.

Currently at Phase 0 — a transport spike only. One read-only tool (houdini_ping). See PHASE0.md for what has been verified, how, and what has not.

Layout

houdini_side/dth_listener.py   runs INSIDE Houdini (started manually)
houdini_mcp/server.py          stdio MCP server (launched by the MCP client)
tests/                         the Phase 0 verification checks
logs/                          audit log, one JSON line per executed command

Setup

python -m venv .venv
.\.venv\Scripts\python.exe -m pip install -r requirements.txt

Run

1. Start the listener inside Houdini (Python Shell, or a shelf tool):

exec(open(r"D:\Development\dth-houdini-mcp\houdini_side\dth_listener.py").read())
start()          # binds 127.0.0.1:8911
status()         # inspect
stop()           # shut down

2. Register the MCP server with your client:

{
  "mcpServers": {
    "dth-houdini": {
      "command": "D:\\Development\\dth-houdini-mcp\\.venv\\Scripts\\python.exe",
      "args": ["D:\\Development\\dth-houdini-mcp\\houdini_mcp\\server.py"]
    }
  }
}

Port is configurable on both sides via DTH_HOUDINI_MCP_PORT (default 8911).

Safety

Phase 0 is read-only: a fixed one-entry command table, loopback-only binding, and nothing that saves or writes the .hip. Every command executed is appended to logs/listener-<pid>.jsonl with its arguments, outcome and duration.

Requests are authenticated. start() writes a per-run token to %LOCALAPPDATA%\dth-houdini-mcp\token; every request must carry it, and it is checked before the command table is consulted. The token is regenerated each run and deleted on stop().

Loopback binding is not a security boundary — a line-oriented parser is reachable from HTTP-shaped traffic, which was measured against an earlier build of this listener and is now blocked two ways (token, plus dropping the connection on the first malformed line). Both are covered by tests/test_crossprotocol.py. The full account is in PHASE0.md §7.

License

MIT © Polynaut

Not affiliated with SideFX or with the DazToHue toolset.