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

Annotations declare readOnlyHint and openWorldHint, and the description meaningfully adds traits those do not cover: per-call pricing ($0.002 USDC via x402 on Base/Solana/Arc), that failed calls are free, and that results are only the first page (up to 20) and not a legal opinion. Those cost, auth and result-depth constraints are exactly the kind of disclosure an invoking agent needs.

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, front-loaded with purpose, then scope boundaries (first page, not a legal opinion), then cost model. Nothing is repeated from the schema and no sentence is filler.

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 two-parameter read-only search with an output schema, the description covers everything an agent needs: what is searched, what comes back, how many results, the legal-status caveat, and the payment mechanism with its failure policy.

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%, with 'term' (3-80 chars) and 'limit' (1-20, default 5) fully documented. The description only restates 'by keyword' and corroborates the 20-result ceiling for limit; it adds no syntax, matching behavior or defaulting detail beyond the schema, so the baseline of 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 ('Searches US CBP binding customs rulings (CROSS database) by keyword') and enumerates exactly what is returned (ruling number, subject, date, tariff number, category, modification/revocation status). It does not explicitly distinguish itself from near neighbors such as logistics_hs_code_classifier or logistics_eu_taric_consultation, so it stops short of a 5.

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?

Usage context is only implied by the data source: an agent can infer this is for looking up existing CBP rulings. There is no explicit when-to-use guidance, no statement of when to prefer hs_code_classifier or the EU/UK tariff tools, and no prerequisites beyond payment.

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