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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered; the description adds real behavioral detail beyond that: the missing-month handling contract, the default-month behavior, the response field `available_months`, and the US$1,000 value unit. It stops short of describing response shape or pagination interaction with `limit`.

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?

Purpose and source are front-loaded in the first clause, and the default/unavailable-month caveat follows logically. The trailing Chinese title is a minor redundancy but plausibly aids matching for a China-dataset tool.

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?

With no output schema, the description carries the burden and does reasonably well: it identifies units, source tables, the default month, and the `available_months` field in the response. It omits response row structure and how `limit` truncation manifests, which keeps it from a 5.

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 four parameters including the `direction` enum and `month` format. The description only restates the commodity filter and default-month behavior, adding little semantic value beyond the schema; 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?

Names a specific verb+resource: China's major export/import commodities in quantity and value, with concrete examples (crude oil, soybeans, iron ore) and source (GACC tables 13/14). It does not, however, explicitly distinguish itself from the near-twin sibling `china_trade_by_commodity`, leaving the agent to infer the difference.

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?

Provides useful operational context — defaults to the latest published month, and a month not yet released by GACC is reported as unavailable rather than guessed — but never states when to prefer this tool over `china_trade_by_commodity` or `china_trade_summary`. Usage is implied rather than routed.

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