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

Annotations already declare readOnly, idempotent, openWorld and non-destructive behavior. The description adds genuinely useful operational context beyond that: it is a free, key-less 'preview endpoint', which warns the agent that results may be a limited subset rather than the full UN Comtrade dataset. It does not discuss rate limits or result truncation specifics, but the preview caveat is real value.

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 short sentences, front-loaded with the verb and resource, with the access caveat and usage note following. No filler or redundancy; every sentence 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?

An output schema exists, so return-value explanation is unnecessary, and the description still conveys access model, data scope, and intended use. The main omissions are the meaning of the 'preview' limitation and the defaults (limit 20, cmdCode TOTAL, flowCode X), which rest on the schema.

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 the schema already documents all five parameters (limit, period, cmdCode, flowCode, reporterCode) in detail. The description only loosely reinforces these by mentioning annual periods, commodity code, reporter, and import/export flows; it adds no syntax or format detail the schema lacks. 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?

States a specific verb and resource ('Fetch UN Comtrade annual trade data for a reporter') and names the return content ('import/export records by commodity code'). It is clearly distinguishable from generic search siblings, though it does not explicitly contrast itself with adjacent statistical tools like un_sdg or world_bank_indicator.

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?

'Use for official bilateral merchandise-trade statistics' gives an implied usage context, and 'free, no key' hints at when it is convenient. But there is no when-not guidance and no reference to an alternative tool for trade data, leaving the agent to infer boundaries itself.

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