shell

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

Annotations already declare the mutation profile (readOnlyHint=false, destructiveHint=false, idempotentHint=false, openWorldHint=false). The description adds real geometric insight beyond that — that outward=True grows the part outward rather than inward — which matters for downstream dimensions. It does not say the operation consumes/modifies the existing solid irreversibly or what happens on failure, so a 3 is right with annotations carrying safety.

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?

Three short, dense sentences with the core action front-loaded and each remaining clause doing unique work on a different parameter. No filler or repetition of the schema.

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?

An output schema exists, so return values need no explanation, and annotations cover the safety profile. The remaining gap is operational context — which body is shelled, whether a pre-selection is required, and error/constraint behavior — but for a three-parameter feature operation this is close to complete.

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 only 33%, so the description must compensate, and it largely does: open_face_points is explained as a list of [x, y, z] points in mm, one per face to remove, with a box-top example and the null-means-closed-hollow case. outward is explained behaviorally. Only thickness_mm is left to the schema, which already documents it.

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?

Specific verb plus resource: 'Hollows the part leaving walls thickness_mm thick' tells an agent exactly what geometry operation this performs. It is clearly distinct from siblings like fillet, chamfer or extrude, though it never names or contrasts an alternative explicitly.

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?

Usage is only implied through parameter behavior — 'none gives a closed hollow part' and 'outward=True adds the walls outside the current surfaces' do tell the agent how to pick a mode. But there is no statement of prerequisites (an active part / existing solid body must exist) or when to prefer shell over another approach.

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