Look up airport / city codes

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

With no annotations, the description must carry the burden of behavioral disclosure. It discloses the tool's ability to handle partial names and return metro codes, which is useful. However, it does not explain what the tool returns (e.g., multiple matches, structure), how it handles ambiguity or no results, or any other edge cases. For a lookup tool, this leaves some uncertainty.

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 long, front-loaded with the core purpose in the first sentence. It is concise, contains no filler, and every sentence adds useful context: the first defines the function, the second provides usage guidance.

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?

The tool is simple (2 parameters, no output schema), and the description provides purpose and usage, but it omits explanation of the 'limit' parameter and does not mention what the response looks like. Given no annotations and no output schema, the description is somewhat incomplete for an agent to fully anticipate the tool's behavior, but it covers the primary intent adequately.

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?

The schema describes the 'query' parameter with examples, and the tool description reinforces its purpose by mentioning partial names and metro codes. However, the 'limit' parameter is not mentioned in the description at all, and its schema lacks a description. With 50% schema coverage, the description does not compensate for the missing limit semantics, leaving the agent to infer its role from the name and constraints alone.

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's function: resolving partial city or airport names to IATA codes. It uses the specific verb 'resolve' and names the resource ('partial city or airport name to IATA codes'). This sets it apart from sibling tools like search_flights or get_itinerary_details, which deal with routing and itineraries.

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 explicitly tells when to use this tool: 'Use this when the user names a place rather than a code, or to find the metro code that covers every airport in a city.' This gives clear context and effectively distinguishes it from alternatives. It also implies that for other operations (e.g., flight search), other tools should be used.

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