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

Annotations already signal safe read-only, idempotent behavior; the description adds meaningful context: source (GACC English 'final' monthly report), units (US$1,000), included metrics, and that partner filtering is a substring match. It does not describe the exact row/table structure returned, but the disclosure is otherwise solid.

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 compact and front-loaded, putting the core output definition and units first. The appended Chinese sentence is redundant with the English text, but it is short and may serve bilingual users, so the structure remains efficient.

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?

For a simple optional-parameter, read-only tool with no output schema, the description covers source, metrics, units, time coverage, and filtering behavior. It does not explicitly state the default output when no partner is provided, but the phrase 'by trading partner country or region' plus optional filter makes this reasonably inferable.

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% and both parameters are already described. The description adds value by explicitly stating that partner is a substring match (not exact match) and by confirming units and period semantics, which helps an agent formulate a valid query.

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 clearly identifies the resource (China's merchandise trade) and granularity (by trading partner country or region), enumerating exports/imports/balance and the time dimensions (month, YTD, YoY % change). It is easily distinguishable from china_trade_by_commodity by mentioning country/region, though it does not explicitly name alternatives.

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 context is implied: this tool is for country/region-level Chinese trade data and supports an optional partner filter. It does not state when to choose it over china_trade_by_commodity or china_trade_summary, nor does it provide exclusion rules, so guidance is implicit rather than explicit.

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