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

Annotations already declare this is a safe, idempotent, read-only, closed-world lookup, so the safety profile is covered. The description adds genuinely useful context beyond that: the data provenance (Taiwan Customs Administration) and that it is synced monthly, plus the fact that the 5% business tax applies unconditionally and that 0% tariff rows still apply to all imports. It does not mention latency or pagination, but neither is likely relevant for a single-code lookup.

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 action and input format, then the returned data, then the sibling routing — a sensible order. The long enumeration of tax-code letters (T/T*, B/B*, C, L*) is somewhat dense and partly redundant with the output schema, but it does communicate the tool's scope, so it mostly earns its place.

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 single-parameter lookup with a full output schema, the description supplies everything else an agent needs: input format, data source and freshness, scope of returned taxes and regulation codes, and when to prefer sibling tools. 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% and the single parameter's description already documents the 4–11 digit format, optional decimal point, and check digit with examples. The description restates the same format constraint ('4–11 碼，可含小數點') without adding syntax or validation semantics 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?

States a specific verb and resource (look up Taiwan CCC tariff codes, 4–11 digits) and enumerates exactly what it returns: tariff rates, business tax, commodity tax, alcohol/tobacco taxes, anti-dumping notices, trade promotion fee, and import regulation codes. This is clearly distinguishable from siblings like lucky_ccc_predict and lucky_import_tax_estimate.

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?

Explicitly routes the agent: 'if you only know the product name, use lucky_ccc_predict first; to compute actual amounts, use lucky_import_tax_estimate.' Both the condition and the alternative tool are named, leaving nothing to inference.

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