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Houdini MCP

Houdini MCP

by beatreichenbach
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
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create_wrangle

Creates an Attribute Wrangle node with specified VEX code in Houdini, letting workflows define custom point or geometry attributes via MCP command execution.

Instructions

Create an Attribute Wrangle node with VEX code.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "parent_path": "<parent_path>",
      "vex_code": "<vex_code>",
      "justification": "<justification>"
    },
    "name": "create_wrangle"
  }
}

Input Schema

NameRequiredDescriptionDefault
nameNo
run_overNoPoints
vex_codeYes
parent_pathYes
justificationYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

C2.7/5.0
Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full behavioral burden and discloses almost nothing. It does not say whether the node is parented/connected automatically, what happens on invalid parent_path, whether the operation is undoable, or what the required 'justification' field is for.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

A single front-loaded sentence with no filler. It is efficient, though its brevity reflects under-specification rather than disciplined editing.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a five-parameter mutation tool with zero schema descriptions, no annotations, and no output schema, an eight-word description is inadequate. An agent cannot confidently supply parent_path or run_over from this definition alone.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0% across five parameters, so the description must compensate and does not. Only vex_code is obliquely referenced; parent_path, name, run_over (default 'Points'), and the mandatory justification field get no explanation at all.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource: 'Create an Attribute Wrangle node'. That is far more precise than a bare 'create_node', but it does not distinguish this from siblings like create_vex_expression or create_node, which an agent could plausibly confuse it with.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

There is no guidance on when to use this versus create_node, create_vex_expression, or set_wrangle_code. The agent is left to infer the choice entirely from sibling names.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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