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

No annotations are provided, so the description carries the burden. It discloses that the tool computes volumes, weight, density, and a verdict, and it specifies the density threshold. However, it does not state that the operation is purely read-only/calculative, how omitted weight_kg is handled, or what happens with invalid inputs beyond schema constraints.

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 a single dense sentence that front-loads the core outputs and threshold. It has no fluff, though the opening phrase 'Packing CBM for cartons' is grammatically awkward and could have been phrased more clearly as a calculation action.

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?

Given one parameter, no annotations, and no output schema, the description names all computed outputs and the decision threshold, which is mostly sufficient for a simple calculator. Gaps remain around the exact meaning of the cube-out/weigh-out verdict and the handling of optional weight_kg, but the tool is simple enough that these are not fatal.

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 100%, so the baseline is 3. The description adds context that inputs are per carton dimensions and that outputs are aggregate volume and density, which slightly reinforces the meaning of the parameters, but it does not provide syntax or conversion details beyond what the schema already conveys.

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 clearly identifies a carton CBM packing calculation and enumerates the outputs: per-line/lot volume, total weight, lot density, and a cube-out/weigh-out verdict. It distinguishes itself from sibling calculators like container_loading by focusing on carton lines, though it lacks an explicit verb such as 'calculate'.

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?

There is no explicit guidance on when to use this tool versus alternatives. The mention of 'same presets as container loading' hints at a relationship with container_loading, but it does not tell an agent when to choose cbm_shipment over container_loading or other volume/density calculators.

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