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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false), and the description adds genuinely new operational context: the UN Comtrade source, the one-commodity scope, and the tier-gated result window (Free = trailing three months, Pro = full series). It stops short of stating auth requirements or pagination behavior.

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 usage trigger is front-loaded in the first clause, followed by return scope, tier limits, and the exclusion in descending order of importance. No sentence is redundant or padded.

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 values need no elaboration; the description covers everything else an agent needs to select and call it correctly - data source, geographic scope, commodity cardinality, result-window limits, and an explicit negative case. Nothing material is missing.

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%, including the flow enum and commodity format example ('lithium', 'NdPr', '283691'), so the schema already carries the parameter burden. The description only implies flow selection via 'import or export' and adds no syntax or format detail beyond what the schema provides, so the 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+resource combination ('Returns US monthly import or export values (UN Comtrade) for one tracked commodity') and names the data source, so the agent knows exactly what class of answer it produces. It also carves itself away from price-oriented siblings with the explicit 'Do not use for spot or futures prices.'

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?

Gives an explicit trigger in user-intent terms ('when the user asks how much ... is being imported or exported, or how trade volumes are trending month to month') and an explicit exclusion (spot/futures prices). Both the when and the when-not are present, so no inference is needed.

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