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

Annotations already declare readOnlyHint/openWorldHint=false/destructiveHint=false, so safety is covered. The description adds genuine behavioral context beyond them: facts come only from official sources, each result carries a link and a checked date, and the output scope is spelled out. It does not discuss latency, caching, or failure behavior for unrecognised products, which keeps it below 5.

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?

Front-loaded with the trigger condition, then the output scope, then provenance and input formats — a sensible information order with no filler sentences. The product-category enumeration is long but justifiable given it defines coverage breadth; it is slightly padded with 'and about 200 more'.

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?

There is no output schema, yet the description enumerates what the response contains (registration route, tariff, VAT, CBEC status, labelling, certification, standards, export value) plus provenance and freshness guarantees. For a read-only lookup tool with a fully documented 2-parameter schema, nothing an agent needs to call or interpret it 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 coverage is 100%, so both parameters are already documented, including the locale enum and the English/Chinese/HS-code formats for 'product'. The description's restatement of accepted product identifiers adds no syntax or constraint detail beyond the schema, 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?

The description names a specific verb ("Says what China requires") and resource (UK product export to China), then enumerates the exact coverage: GACC registration, tariff/VAT, CBEC route, labelling, certification, standards, 2025 export value. The example product list and 'about 200 more' make the scope concrete enough to distinguish it from siblings like find_duty_rate or find_uk_compliance.

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 when the user asks what it takes to export a UK product to China" is an explicit, actionable trigger condition with a concrete domain. It does not, however, name any alternative tool or state when NOT to use it — an agent facing a bare duty-rate question has no guidance on whether this tool or find_duty_rate is the right call.

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