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

With no annotations, the description carries the full behavioral burden. It usefully discloses that the estimate includes all stacking layers plus MPF/HMF and that the response includes official sources and an as-of date, but it says nothing about permissions, rate limits, accuracy caveats, or whether the operation is read-only.

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?

Three compact sentences with the core purpose front-loaded, followed by the key input constraint and output note. Nothing is wasted, though the return-value sentence could be folded in slightly more tightly.

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 7-parameter computation tool with no annotations, no output schema, and only 29% schema description coverage, the description is too thin. It explains what is computed and partially what is returned, but leaves the agent without guidance on most inputs or on input format expectations.

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 only 29% and the description does not mention any input parameter directly. It hints at product_description via 'plain product description' and broadly implies freight/insurance/broker_fee through 'landed cost,' but origin_code, arrival_mode, and declared_value receive no clarification, leaving the low coverage uncompensated.

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 uses a specific verb (Estimate) and resource (total US customs duty, MPF/HMF, landed cost), and scopes it to a plain product description with no HTS code required. This clearly distinguishes it from the sibling list_tariff_categories tool, which is a browsing operation rather than a computation.

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 usage context: 'from a plain product description' and 'No HTS code required,' which tells an agent this is the right tool when no classification code is available. It does not explicitly state when not to use it or name the sibling alternative, so it falls just short of a 5.

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