Set a VEX expression on a specified Houdini node parameter using provided code, enabling procedural parameter control.
Set a VEX expression on a parameter.
Args: node_path: Path to the node. parm_name: Parameter name. vex_code: VEX expression code.
| Name | Required | Description | Default |
|---|---|---|---|
| vex_code | Yes | ||
| node_path | Yes | ||
| parm_name | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description bears full responsibility for disclosing behavioral traits. It only states the action (setting) without mentioning side effects, prerequisites (e.g., whether the parameter must exist), reversibility, or potential errors. For a mutation tool, this is insufficient disclosure.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is concise and well-structured: a one-sentence action statement followed by a clear parameter list. It is front-loaded with the core purpose and avoids unnecessary words, though it could be expanded with useful context without sacrificing brevity.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with 3 required parameters, no annotations, and no output schema, the description omits critical details such as value formats, error conditions, whether the parameter must already exist, and the effect on existing expressions. It is incomplete for an agent to call it correctly without additional inference.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
With 0% schema coverage, the description must compensate by explaining parameter semantics, but it merely restates the parameter names with minimal phrases (e.g., 'Path to the node', 'Parameter name', 'VEX expression code') that add little beyond the schema. It does not provide expected formats, examples, or relationships between parameters.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action: setting a VEX expression on a parameter. It specifies the resource (parameter) and the type of value (VEX expression), which distinguishes it from siblings like set_parameter (generic value) and set_expression (possibly generic expression). The parameter list further reinforces the specific purpose.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides no guidance on when to use this tool versus alternatives such as set_expression, validate_vex, or set_parameter. It does not mention any exclusions or conditions for selection, leaving the agent to infer the appropriate context from the name and parameter list alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.