Evaluate Houdini expressions in hscript or Python and return the result for scene building, simulation, or rendering tasks.
Evaluate an expression in Houdini and return its result.
Args: expression: Expression string to evaluate. language: Expression language, "hscript" or "python".
| Name | Required | Description | Default |
|---|---|---|---|
| language | No | hscript | |
| expression | Yes |
Changes observed during successful MCP inspections.
v2.24.1Input schema / additionalPropertiesAdded value: +falsev0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full disclosure burden. It notes a return result but says nothing about side effects even though evaluating hscript or python can mutate the scene, nor about errors, cost, or whether execution is sandboxed. For a code-evaluation tool with zero annotation coverage this is a notable gap.
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 action statement is front-loaded in the first sentence and the per-argument notes are compact. There is no filler, though the bare 'Args:' block is functional rather than polished.
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?
With no output schema and no annotations, the description should do more for a tool that executes arbitrary code. It covers the two parameters at a basic level but omits defaults, side-effect risk, and return-shape details, leaving an agent with an incomplete picture for a 2-parameter eval tool.
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?
Schema description coverage is 0%, so the description must compensate, and it usefully enumerates the allowed language values ('hscript' or 'python'), which the schema does not express as an enum. It does not state the default (hscript) or the required/optional status of expression, so it partially compensates.
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 gives a clear verb+resource ('Evaluate an expression in Houdini') and states it returns a result, so an agent knows what the tool does. However, it does not distinguish itself from close siblings like execute_hscript, execute_python, or set_expression, leaving the agent to infer the boundary.
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?
There is no explicit when-to-use or when-not-to-use guidance, and no mention of the near-identical siblings execute_hscript and execute_python. The only implied guidance is that you supply an expression, which is too thin to route the agent reliably.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.