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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower; the description still adds real behavioral value by disclosing the return shape (period covered, imports, exports, net position, lead partner) and a tier-gated capability difference for Pro. It does not mention units, coverage windows, or behavior when a commodity is ambiguous, so it is good but not exhaustive.

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 sentences, each carrying distinct payload: trigger, examples, return contents plus tier note. The use case is front-loaded and there is no filler or restatement of the tool name.

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 documentation is not strictly required, yet the description still summarizes the payload. Combined with full schema coverage and a complete annotation set, an agent has enough to call this correctly; only minor operational details (units, period format, ambiguous-commodity handling) are absent.

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?

With one parameter at 100% schema coverage, the baseline is 3, but the description goes further by giving concrete commodity examples (branded product names like nickel MHP, NdPr oxide) that show what a valid

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 ('quick picture of the trade position or main source countries for a critical mineral') and grounds it with concrete examples (lithium carbonate, cobalt hydroxide, nickel MHP, NdPr oxide). It also enumerates the returned fields, so the agent knows exactly what this tool produces. It does not explicitly contrast itself with the sibling search_trade_flows, which is the main remaining gap.

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?

Opens with an explicit trigger ('Use this when the user wants a quick picture...'), giving clear when-to-use context for the exploratory/summary case. The closing note that Pro 'adds the full partner-country breakdown with shares' implicitly signals the boundary against a deeper trade-flow search, but no alternative tool is named or excluded outright.

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