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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does disclose the output format (lightweight summary rows with listed fields) and the cap of 200 rows per call, which is useful. However, it omits potential behavioral details such as pagination, behavior on empty results, error handling, or whether filters are exact/case-sensitive, leaving some ambiguity for an agent.

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 with no fluff. It front-loads the core purpose, mentions the source and scale, lists the output fields, points to an alternative, and states the row cap—all efficiently. Every sentence earns its place, making it highly concise and well-structured.

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 list tool with no output schema, the description provides sufficient context: the source, filters, output fields, and row limit. It also directs the agent to get_metro for detailed data, which covers the main use case. It does not mention sorting order (implied by 'ranked') or edge-case behavior, but these are minor gaps given the tool's simplicity.

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 description coverage is 100%, so the parameters (n, region, country) are already well-documented in the input schema. The description only reiterates that filtering by region or country is optional and mentions the cap, which is already in the schema. It adds minimal semantic value beyond what the schema provides, so a baseline score of 3 is appropriate.

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: it returns a ranked list of metros from a specific composite, with optional filters by region or country, and describes the output fields. It also distinguishes itself from get_metro by explicitly pointing to that tool for full detail, making the purpose unambiguous.

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 a clear usage hint by saying 'Call get_metro for full detail on any one metro,' which implicitly tells the agent when to use this list tool versus the detail tool. However, it does not explicitly mention when to use alternatives like search_metros or compare_metros, nor does it state when not to use this tool, so it stops short of full exclusionary guidance.

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