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

Annotations already provide readOnlyHint=true and destructiveHint=false, but the description adds critical behavioral context beyond that: the corpus covers 2017-present, is mirrored from CBP CROSS, has backfill in progress, and discloses coverage count in every response. It also notes that no API key is required. This goes well beyond the annotation hints and helps the agent manage expectations.

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 two sentences, front-loaded with the core purpose and immediately followed by query modes, return contents, and corpus limitations. Every clause earns its place; no filler or redundant restating of the tool name.

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?

With no output schema, the description must explain return values, and it does: classified codes, dates, precedent links, and official CBP document link. It also provides corpus scope and a caveat about backfill, covering the main context an agent needs to interpret results correctly. The parameter semantics are sufficiently covered, making this a complete description.

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 the baseline is 3. The description adds meaning to the query parameter by specifying that it accepts HS codes of 2-10 digits or keywords, which the schema only hints at with examples. It does not add detail for limit, but the schema already documents its default and max, so the added query semantics justify a 4.

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 starts with a specific verb and resource: 'Search US Customs (CBP) classification rulings.' It clearly distinguishes this from sibling tools by framing it as 'the case law of HS codes,' which conveys a unique purpose. It also states what queries and result types are returned, leaving no ambiguity about the tool's function.

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 gives clear usage context: query by HS code (2-10 digits) or keywords, and returns rulings with specific attributes. It does not explicitly name alternative tools or state when not to use this tool, but the context is clear enough for an agent to select it for ruling lookups.

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