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

With no annotations, the description carries the full burden of behavioral disclosure. It usefully reveals that the tool does not invent duty rates and defaults to 0, which is an important honesty behavior. However, it does not disclose whether freight rates are live quotes or static reference estimates, and it says nothing about side effects or permissions.

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 compact sentences with the core computation front-loaded and no filler. The formula sentence earns its place by explaining how the components combine, and nothing is repeated from structured data unnecessarily.

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?

For a 6-parameter calculator with a rich input schema and an output schema, the description is largely sufficient: it gives the formula and the key duty-rate behavior. It could be more complete by routing to sibling tools or stating freight-rate assumptions, but those are minor given the schema and output schema coverage.

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 value by presenting the exact formula tying unit_cost, freight, duty, and other_fixed_cost together, and it clarifies overhead examples like labeling/QC/packaging. This is a real semantic improvement over the schema alone, though not a large one.

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 verb-resource pair ('计算单件落地成本') and gives the full formula, so an agent can tell this computes per-unit landed cost rather than profit or breakeven. However, it does not explicitly name or differentiate from sibling tools breakeven_price and estimate_profit, so it misses the strongest form of differentiation.

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?

The description gives clear calculation context and even advises using export-compliance's HS tool for duty classification because the tool defaults duty to 0 and does not fabricate rates. It does not state when to use this tool versus breakeven_price or estimate_profit, nor does it give any when-not-to-use guidance.

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