Look Up Census Trade CTY_CODE

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

Annotations already establish read-only, idempotent, non-destructive behavior, and the description adds context beyond that: the API filters by numeric CTY_CODE rather than country name, CTY_NAME cannot be used as a filter, and return values include code, name, and ISO alpha-2 details. It also flags special naming for North/South Korea. This is valuable behavioral transparency, though it doesn't mention rate limits or match-failure behavior.

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 well-structured with intro, Args, Returns, and Examples sections, and it front-loads the core purpose and sibling relationship. It is somewhat longer than strictly necessary because the Args section repeats schema properties, but every other part contributes useful context such as API filtering behavior and usage examples.

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 lookup tool with no output schema, the description is complete: it explains what the tool returns, the special case of country groupings, naming caveats, and how to chain the result into sibling tools. It covers when to use, when not to use, and gives concrete examples, so an agent can select and invoke it correctly without additional information.

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 fully documents all three parameters with defaults, enums, and constraints. The description's Args section largely restates this information, though the examples ('korea', 'vietnam', 'european union') and the note about partial name matching add modest practical meaning beyond the schema.

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 states the tool 'looks up' Census Bureau Schedule C CTY_CODE, including country groupings, and explicitly links this to filtering census_trade_query_exports/imports by country. This specific verb+resource framing and the mention of sibling tools distinguishes it from the query/list/dataset siblings.

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 guidance: 'Use this tool to translate a country name into the code you need', plus concrete 'Use when' examples for Vietnam and European Union. It also gives an exclusion: 'Don't use when: You already have the CTY_CODE - go straight to census_trade_query_exports/imports', naming the alternative tool.

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