Set the surface water material on an Unreal Engine water body by actor label and material asset path.
Set the surface water material on a water body (resolved by asset path).
Returns: { water_body_label: string, material: string, set: bool }
| Name | Required | Description | Default |
|---|---|---|---|
| material_path | Yes | Asset path of the UMaterialInterface to assign | |
| water_body_label | Yes | Label of the AWaterBody actor |
Changes observed during successful MCP inspections.
v1.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false, so the safety profile is covered. The description adds the return tuple shape, which is useful since no output schema exists, but it does not say that an existing material is replaced, whether the operation is undoable, or what happens on failure. A 3 is appropriate given the annotation coverage.
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?
Two short sentences, purpose front-loaded, and the return shape is presented compactly. Nothing is padded, though the return signature could arguably be dropped if an output schema existed.
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 two-parameter mutation with full schema coverage and annotations covering the safety profile, the description supplies the one thing structured data does not: the return tuple. Missing only failure-mode behavior (invalid label or material path), which is a minor gap.
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 coverage is 100% and both parameters are documented in the schema, so the description is not required to carry parameter meaning. The mention of 'asset path' loosely echoes material_path but adds no syntax, format, or constraint detail beyond the schema. Baseline 3 applies when the schema does the heavy lifting.
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?
States a specific verb and resource — set the surface water material on a water body — which distinguishes it cleanly from siblings like set_water_body_properties and set_water_body_gerstner_waves. The parenthetical '(resolved by asset path)' is slightly ambiguous since the actor is addressed by label while the material is a path, but the core purpose is unambiguous.
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?
No when-to-use context, no mention of alternatives such as set_water_body_properties, and no prerequisites (e.g., the water body actor must exist, material must be a UMaterialInterface). The agent gets no routing guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.