mass_properties

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

With no annotations, the description carries the full load and does well: it discloses units (g, mm, g*mm2), the reference frame for the inertia tensor (about the combined centre of mass, world axes), the density resolution precedence (per-object material, then material/density_kg_m3 overrides applied to all objects), and the degradation path when material is missing.

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 output quantities and their units are front-loaded in the first clause, followed by the density-resolution rules. It is dense but every sentence adds information; the only cost is a slightly run-on second sentence.

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 the description needn't enumerate return values, yet it goes further by specifying units and frames that matter for interpretation. Coverage of the density fallback is complete; the remaining gap is the scope semantics of the objects parameter and the doc handle.

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 and only partly does. It clarifies the semantics of material and density_kg_m3 (overrides applying to all objects) but leaves doc and objects unexplained, including what happens when objects is null or omitted.

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 names the exact computed quantities (volume, mass, centre of mass, inertia tensor) and their units, so an agent knows precisely what the tool returns. It stops short of naming how it differs from siblings like bom or document_info, which also surface physical/aggregate data.

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 implied rather than stated: the description explains that density comes from each object's material unless overridden, and that objects without material report volume only, which implicitly tells the agent when results will be partial. There is no explicit when-to-use guidance, no mention of alternatives such as bom, and no statement of prerequisites for the referenced set_properties step.

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