rhino_assign_material

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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false. The description adds the constraint that the material must be an 'existing' one, which is not in the annotations. However, it does not explain what happens if the material name is invalid, whether the operation is reversible, or the effect on the objects. The added context is limited but not contradictory.

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 a single, efficient sentence with no filler. It front-loads the core action and is appropriately concise for the tool's complexity. It loses a point for being perhaps too sparse, but it is not overwrought.

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?

The tool has an output schema, so the description doesn't need to explain return values. However, the description omits critical operational context: whether the material must exist beforehand (implied but not explicitly stated), how to find valid material names, error handling if objects are invalid, and any prerequisites. For a simple tool this might be acceptable, but the lack of any examples or usage notes makes it incomplete for reliable autonomous invocation.

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 for parameter documentation. The description does not mention guids or material_name at all, nor how to specify them. The schema itself only provides minimal phrasing ('GUIDs of objects', 'Material name to assign'), which is insufficient for the agent to construct correct input without further inference.

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 is specific: 'Assign an existing material to objects' names the verb, resource, and object. It clearly indicates that the material must already exist (as opposed to creating one). However, it does not explicitly distinguish itself from the sibling rhino_set_material, so it earns a 4 rather than a 5.

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 gives no guidance on when to use this tool versus alternatives like rhino_set_material or rhino_create_material. There are no explicit conditions, exclusions, or references to other tools, leaving the agent to infer usage context on its own.

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