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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds meaningful behavioral detail beyond that: it returns binding and informational ruling letters, specifies the fields returned, and notes whether a ruling was later modified or revoked. This gives the agent a clear picture of the operation's result and limitations.

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 information-dense and front-loaded, with the core action in the first sentence interloping. Later sentences add return fields, use cases, and search modes, all of which are useful. It is slightly longer than necessary because it restates search modes already present in the schema, but there is no fluff.

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 explicitly enumerates the returned fields and ruling types, so an agent knows what to expect. It gives concrete examples, supported by schema examples, and covers query modes, result types, and use cases. For a read-only search tool with annotations present, this is sufficiently complete.

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 thoroughly, including query examples and the format for hts and since. The description reinforces that queries can be product descriptions, HTS codes, or ruling numbers, but adds little semantic meaning beyond what the schema provides. It therefore meets the baseline but does not exceed it.

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 a specific verb and resource: 'Search CBP CROSS — the US Customs and Border Protection ruling letters database.' It states the purpose accurately and lists the main output fields. However, it does not explicitly distinguish itself from the sibling tool 'cross_ruling,' so the differentiation criterion for a 5 is not fully met.

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 description provides explicit use context: 'Use this to find tariff classification precedent for an import' and enumerates concrete use cases like HTS classification, country-of-origin determinations, USMCA/NAFTA eligibility, and valuation rulings. It does not explicitly state when not to use this tool or recommend an alternative, so it stops short of a 5.

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