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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive behavior. The description adds value by disclosing what the full response contains: facts, analysis, holding, HTS numbers, issue date, and modification/revocation relationships. No contradiction with 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 compact, front-loaded with the core action, and uses the rest of the sentence to enumerate exactly what the returned ruling letter contains. No filler and every clause adds useful information.

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 simple two-parameter read-only tool with rich annotations, the description fully explains the return value and the context of use. Even without an output schema, the agent knows what to expect back and when to invoke the tool.

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%, with both parameters already described in the schema. The description adds a small amount of context by clarifying that ruling_number comes from cross_search and that ruling letters run long, but the schema already carries the main semantic load.

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: 'Get one CBP CROSS customs ruling letter in full by its ruling number.' It also names the source of the number, cross_search, which distinguishes this retrieval tool from the search sibling without needing to open either schema.

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?

Provides clear context: use this to read the actual reasoning behind a tariff classification precedent before relying on it. It also points to cross_search as the source for ruling numbers. It does not explicitly spell out when not to use it, but the intended use is well implied.

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