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Houdini MCP

Houdini MCP

by beatreichenbach
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Local

assign_material

Assign a material to a geometry node by creating a Material SOP that links the geometry and material paths for correct shading.

Instructions

Assign a material to a geometry node via a Material SOP.

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": {
      "geo_path": "<geo_path>",
      "material_path": "<material_path>"
    },
    "name": "assign_material"
  }
}

Input Schema

NameRequiredDescriptionDefault
geo_pathYes
material_pathYes

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?

No annotations exist, so the description carries the full disclosure burden. It names the mechanism (Material SOP) but says nothing about whether a new SOP is created or an existing one modified, whether it mutates the scene destructively, or whether paths must resolve to existing nodes.

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 zero filler; the action and mechanism come first. 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?

A mutation tool with no annotations, no output schema, and fully undocumented parameters needs substantially more than one sentence. Key facts an agent needs to call it correctly, such as path formats and side effects, are absent.

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%, so the two required parameters are documented only by bare titles 'Geo Path' and 'Material Path'. The description loosely implies both but adds no path syntax, format expectations, or what happens when a path is invalid.

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?

States a specific verb and resource: assigning a material to a geometry node, plus the mechanism (Material SOP). An agent knows what the tool does, though it doesn't distinguish itself from siblings like create_material or get_material_info.

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?

No guidance on when to use this versus creating or querying materials, and no prerequisites such as whether the material or geo node must already exist. The agent must infer the workflow context entirely.

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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