add_material_attribute_layers_node

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

Goes well beyond the annotations: it explains that bUseMaterialAttributes disables the separate pins (Base Color etc.), that the call is not idempotent (each call adds another node), and that it fails when the save fails. This is exactly the mutation/disruption context annotations alone cannot provide.

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?

Well front-loaded: action verb, then side effects, then caveats, then returns. Dense but nearly every clause carries information; the explicit return enumeration is somewhat verbose given no output schema, keeping it just below a 5.

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 mutating, non-idempotent graph-editing tool with no output schema, the description supplies the return fields, the failure condition, and the semantic effect on the material, so nothing an agent needs to call it safely is missing.

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 100%, and the schema already explains node_name is only an echoed label and material_path is an object path. The description's return block references node_name but adds no new parameter semantics, so baseline 3 applies.

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 (adds a MaterialAttributeLayers expression to a UMaterial), and enumerates the concrete side effects (toggles bUseMaterialAttributes, wires into MaterialAttributes, recompiles, saves). An agent can distinguish this from the many generic material-graph siblings without opening the schema.

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?

Conveys useful context (non-idempotent, save-failure behavior) but never states when to prefer this over alternatives like create_material_expression or connect_to_material_output, nor prerequisites. Usage is implied by the purpose rather than stated.

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