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

Annotations already establish readOnlyHint=true, destructiveHint=false and a closed-world scope, so the safety profile is covered. The description adds real behavioral context beyond that: output is an estimate (not exact), it operates on a single carton line of identical cartons, container counts are volume-only, and it is explicitly not a simulation or a quote. It says nothing about precision limits or units beyond what the schema implies, keeping it short of a 5.

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 sentences, front-loaded with the triggering condition and then the outputs, followed by scope boundaries. No filler or restated tool name; every clause carries information.

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 what is returned (CBM, shipment weight, container counts) and what is not (simulation, quote). Annotations handle safety, and all params are schema-documented. The only minor gap is that accuracy/rounding expectations of an 'estimate' are not quantified.

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 every parameter (dimensions, carton_count, weight_per_carton_kg, locale) is already documented in the schema. The description only reinforces the 'one carton line' framing and that weight is part of the output; it adds no format, unit-conversion, or edge-case detail beyond the structured fields. Baseline 3 applies.

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 a specific verb (estimates) and concrete outputs (CBM, shipment weight, volume-only 20ft/40ft/high-cube container counts) plus the input shape (one carton line). It explicitly contrasts itself with adjacent concepts ('not a loading simulation or a freight quote'), letting an agent distinguish it from siblings like estimate_landed_cost or compare_sea_and_air.

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 gives a clear triggering condition ('Use when the user asks for the CBM of a shipment or how many containers a carton line needs') and explicit exclusions (not a loading simulation, not a freight quote). It does not, however, route the agent to a named sibling tool for the excluded cases, so the alternative-selection guidance is incomplete.

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