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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description adds value by disclosing corpus limits (2017-present, backfill in progress), that coverage count is included in every response, and that no API key is required. It also specifies what each ruling contains, giving the agent a realistic expectation of the data without contradicting annotations.

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 three sentences, each serving a distinct purpose: defining the tool's role, explaining how to query and what to expect, and setting expectations about corpus scope and access. There is no redundant or filler content; the structure is front-loaded and information-dense.

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 search tool with no output schema, the description adequately covers key aspects: the input method, the type of results returned, the temporal/corpus limitations, and the access requirements. It provides enough detail for an agent to decide when to invoke the tool and what to expect in the response, making it situationally 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 coverage is 100%, so the baseline is 3. The description goes beyond the schema by specifying the HS code digit range (2-10 digits) and providing a concrete example('electric standing desk'), which clarifies query formatting and acceptable inputs. This additional detail raises the score above baseline.

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 opens with a specific verb-resource pair ('Search US Customs (CBP) classification rulings') and immediately differentiates the tool from sibling data tools by framing it as 'the case law of HS codes' and explaining how the border interprets products. This clearly establishes a unique purpose beyond generic search tools.

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?

It gives clear usage context by stating that queries can be HS codes (2-10 digits) or keywords, and explains the nature of the results (classified codes, dates, precedent links). It does not explicitly name alternative tools or state when not to use it, but the context is enough to guide appropriate use without confusion.

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