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

Beyond the read-only and non-destructive annotations, the description adds substantive behavioral context: data is 'mirrored and revision-tracked' (implying results may be revised), coverage starts '2017→present (HS6 detail from 2024)', and it warns 'The customs value here excludes duty, so never compare invoice $/kg across origins without it.' It also notes 'No API key required.' No contradiction with annotations.

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 paragraph but front-loaded with the core purpose. Each sentence adds substantive information, though it could be broken into clearer segments. It is appropriately sized for the complexity of the tool, 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?

Given the complex conditional behavior, rich schema, and output schema, the description fully covers data coverage, return values, caveats, examples, and authentication. It doesn't need to explain share_draft because the schema already covers it, and output schema handles return details.

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 baseline is 3. The description adds conditional semantics: 'When you give an origin and a 6-digit commodity it ALSO returns duty and landed_vs' and specifies example values ('China, Vietnam, India — 30 largest origins', 'us_la_longbeach, savannah'), going beyond the schema's basic parameter descriptions.

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 opens with a specific verb and resource: 'Query US containerised import trade directly: monthly weight (kg) and customs value (USD) through the 8 major US container gateways, filterable by origin country... commodity... and gateway.' It clearly distinguishes from the compare sibling by stating 'no need to call compare' for landed-cost comparisons.

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 explicitly states when not to use an alternative: 'That is the buyer-pitch number, answered in this one call — no need to call compare.' It also provides concrete example queries ('Ask it things like: US furniture imports from Vietnam monthly; plastics through Houston; imports from India last 36 months') illustrating when to invoke the tool.

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