add_shell

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

With no annotations, the description carries the full burden. It discloses that the tool modifies geometry (hollows the part) and returns mass properties, which is important context. However, it does not mention destructive nature (permanent modification), potential side effects like altering existing features, or error conditions. It adds some value beyond the schema but has gaps.

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 concise (two sentences) and front-loads the core operation. It efficiently explains the open_face parameter in the second sentence. No wasted words, though it could be slightly more structured, but it's appropriately sized for the tool's complexity.

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 description covers the primary operation and parameter semantic, but lacks details on return format (even though output schema is absent), prerequisites (e.g., must be a solid part), and edge cases like multiple faces or non-cuboid shapes. For a tool with 2 parameters and no output schema, it is functional but misses some completeness.

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?

The schema description coverage is 0%, so the description must explain parameters. It does: open_face is clearly described with possible values and meanings, and thickness_mm's purpose is implied by 'wall of thickness_mm'. The description provides meaning that the schema lacks, making it highly valuable for correct parameter usage.

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 states a specific verb ('Hollow') and the resource ('current part'), and clarifies that it transforms the part by creating a wall of given thickness. It also explicitly defines the open_face parameter's effect, making the tool's purpose unambiguous. This distinguishes it from sibling modeling tools like add_box or add_shell's related operations.

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 implies usage for hollowing operations but does not specify when to use this versus alternatives like cut_profile or add_hole. It lacks explicit context about part requirements (e.g., must be a solid with at least one face) or scenarios where a different tool is more appropriate. However, it does convey the core operation clearly enough for an agent to infer basic usage.

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