mass_properties

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

With no annotations, the description carries the full burden and does disclose meaningful behavior: a pure read/compute tool that returns a fixed set of quantities, the exact units, and the side effect that supplying density adds mass. It does not address permissions or handle validity, but for a non-mutating computation there is little remaining behavioral risk to expose.

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?

Two tight sentences that are front-loaded with the returned quantities and units, then the conditional density behavior and reference values. Every clause earns its place with no filler.

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?

With no output schema, the description usefully enumerates return values and units, and it fully explains the optional density parameter. The only gap is the unexplained required handle, which slightly limits completeness given the total absence of structured field documentation.

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 0%, so the description must compensate, and it does strongly for density: it gives units (kg/mm³), the conditional effect (mass in kg), and concrete reference values for steel, aluminum and ABS. The handle parameter is left unexplained, so coverage is not complete.

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 computation ('mass properties of a shaped object') and enumerates the exact outputs (volume, surface area, centroid, bounding box, inertia tensor, conditional mass), which is far more specific than a name restatement. It does not, however, explicitly distinguish itself from the overlapping sibling bounding_box, whose output it partly subsumes.

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?

It hints at usage via the conditional 'If density is given, also returns mass,' but never states when to prefer this tool over measure_distance or bounding_box, nor any prerequisites for the handle. Usage is only implied.

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