Union every body

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

Annotations only contain a title, so the description carries the behavioral burden. It states that the operation merges all modifiable solid bodies, implying a mutation. However, it does not disclose side effects such as whether original bodies are removed, whether the operation is destructive, or failure conditions (e.g., what happens if no bodies are modifiable). It also does not mention that this adds a feature to the tree. This is a minimal but honest description; it conveys the core behavior without contradiction.

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 two sentences with no filler. The primary action is front-loaded ('Merge all modifiable solid bodies into one'), and the second sentence provides a practical use case. Every word earns its place, and the structure is optimal for quick comprehension.

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?

Given the tool's simplicity and that the schema fully documents parameters, the description covers the essential purpose and context. It explains what the tool does and when to use it, which is enough for an agent to select and call it. The lack of an output schema means return values are not expected to be detailed, and the description does not need to explain them. Minor gaps exist (e.g., failure behavior), but overall it is complete for its role.

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%, so all five parameters already have detailed descriptions in the schema. The tool description adds no parameter-specific information beyond what the schema provides. Per the rubric, when coverage is high, the baseline is 3. The description does not clarify any parameter semantics further, which is acceptable.

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: 'Merge all modifiable solid bodies into one.' It identifies the resource (solid bodies) and the operation (union). It also adds context about the typical use case ('cleanup before exporting a single part'), which helps an agent understand when it applies. The phrase 'all modifiable' distinguishes it from a generic boolean tool like onshape_boolean.

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 a clear use case: 'The usual cleanup before exporting a single part.' This signals when an agent should consider this tool. It does not explicitly name alternatives or exclusions (e.g., when to use onshape_boolean instead), but the context implies it is for merging everything into one body. This is sufficient guidance for most scenarios, though explicit sibling differentiation would be stronger.

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