TouchDesigner Integration (twozero MCP)

CRITICAL RULES

1. NEVER guess parameter names. Call td_get_par_info for the op type FIRST. Your training data is wrong for TD 2025.32.
2. If tdAttributeError fires, STOP. Call td_get_operator_info on the failing node before continuing.
3. NEVER hardcode absolute paths in script callbacks. Use me.parent() / scriptOp.parent().
4. Prefer native MCP tools over td_execute_python. Use td_create_operator, td_set_operator_pars, td_get_errors etc. Only fall back to td_execute_python for complex multi-step logic.
5. Call td_get_hints before building. It returns patterns specific to the op type you're working with.

Architecture

Hermes Agent -> MCP (Streamable HTTP) -> twozero.tox (port 40404) -> TD Python

36 native tools. Free plugin (no payment/license — confirmed April 2026). Context-aware (knows selected OP, current network). Hub health check: GET http://localhost:40404/mcp returns JSON with instance PID, project name, TD version.

Setup (Automated)

Run the setup script to handle everything:

bash "${HERMES_HOME:-$HOME/.hermes}/skills/creative/touchdesigner-mcp/scripts/setup.sh"

The script will:

1. Check if TD is running
2. Download twozero.tox if not already cached
3. Add twozero_td MCP server to Hermes config (if missing)
4. Test the MCP connection on port 40404
5. Report what manual steps remain (drag .tox into TD, enable MCP toggle)

Manual steps (one-time, cannot be automated)

1. Drag ~/Downloads/twozero.tox into the TD network editor → click Install
2. Enable MCP: click twozero icon → Settings → mcp → "auto start MCP" → Yes
3. Restart Hermes session to pick up the new MCP server

After setup, verify:

nc -z 127.0.0.1 40404 && echo "twozero MCP: READY"

Environment Notes

• Non-Commercial TD caps resolution at 1280×1280. Use outputresolution = 'custom' and set width/height explicitly.
• Codecs: prores (preferred on macOS) or mjpa as fallback. H.264/H.265/AV1 require a Commercial license.
• Always call td_get_par_info before setting params — names vary by TD version (see CRITICAL RULES #1).

Workflow

Step 0: Discover (before building anything)

Call td_get_par_info with op_type for each type you plan to use.
Call td_get_hints with the topic you're building (e.g. "glsl", "audio reactive", "feedback").
Call td_get_focus to see where the user is and what's selected.
Call td_get_network to see what already exists.

No temp nodes, no cleanup. This replaces the old discovery dance entirely.

Step 1: Clean + Build

IMPORTANT: Split cleanup and creation into SEPARATE MCP calls. Destroying and recreating same-named nodes in one td_execute_python script causes "Invalid OP object" errors. See pitfalls #11b.

Use td_create_operator for each node (handles viewport positioning automatically):

td_create_operator(type="noiseTOP", parent="/project1", name="bg", parameters={"resolutionw": 1280, "resolutionh": 720})
td_create_operator(type="levelTOP", parent="/project1", name="brightness")
td_create_operator(type="nullTOP", parent="/project1", name="out")

For bulk creation or wiring, use td_execute_python:

# td_execute_python script:
root = op('/project1')
nodes = []
for name, optype in [('bg', noiseTOP), ('fx', levelTOP), ('out', nullTOP)]:
    n = root.create(optype, name)
    nodes.append(n.path)
# Wire chain
for i in range(len(nodes)-1):
    op(nodes[i]).outputConnectors[0].connect(op(nodes[i+1]).inputConnectors[0])
result = {'created': nodes}

Step 2: Set Parameters

Prefer the native tool (validates params, won't crash):

td_set_operator_pars(path="/project1/bg", parameters={"roughness": 0.6, "monochrome": true})

For expressions or modes, use td_execute_python:

op('/project1/time_driver').par.colorr.expr = "absTime.seconds % 1000.0"

Step 3: Wire

Use td_execute_python — no native wire tool exists:

op('/project1/bg').outputConnectors[0].connect(op('/project1/fx').inputConnectors[0])

Step 4: Verify

td_get_errors(path="/project1", recursive=true)
td_get_perf()
td_get_operator_info(path="/project1/out", detail="full")

Step 5: Display / Capture

td_get_screenshot(path="/project1/out")

Or open a window via script:

win = op('/project1').create(windowCOMP, 'display')
win.par.winop = op('/project1/out').path
win.par.winw = 1280; win.par.winh = 720
win.par.winopen.pulse()

MCP Tool Quick Reference

Core (use these most):

Read/Write:

Visual:

Search:

System:

Input Automation:

The table above covers the 32 tools used in typical creative workflows. The remaining 4 tools (td_project_quit, td_test_session, td_dev_log, td_clear_dev_log) are admin/dev-mode utilities — see references/mcp-tools.md for the full 36-tool reference with complete parameter schemas.

Key Implementation Rules

GLSL time: No uTDCurrentTime in GLSL TOP. Use the Values page:

# Call td_get_par_info(op_type="glslTOP") first to confirm param names
td_set_operator_pars(path="/project1/shader", parameters={"value0name": "uTime"})
# Then set expression via script:
# op('/project1/shader').par.value0.expr = "absTime.seconds"
# In GLSL: uniform float uTime;

Fallback: Constant TOP in rgba32float format (8-bit clamps to 0-1, freezing the shader).

Feedback TOP: Use top parameter reference, not direct input wire. "Not enough sources" resolves after first cook. "Cook dependency loop" warning is expected.

Resolution: Non-Commercial caps at 1280×1280. Use outputresolution = 'custom'.

Large shaders: Write GLSL to /tmp/file.glsl, then use td_write_dat or td_execute_python to load.

Vertex/Point access (TD 2025.32): point.P[0], point.P[1], point.P[2] — NOT .x, .y, .z.

Extensions: ext0object