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

Annotations already indicate readOnly, openWorld, and idempotent behavior, lowering the burden on the description. The description adds useful behavioral context beyond annotations: it does not return the complete stop list and requires a search term, while also disclosing the returned fields.

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 a single focused sentence that front-loads the core search behavior, then adds the return-value summary and the key usage constraint. Every clause earns its place, and there is no redundant repetition of schema or annotation 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?

Without an output schema, the description compensates by naming the returned fields (code, lines, coordinates) and the follow-up tool. It also covers the essential input condition and the main behavioral limitation, making the tool self-sufficient for an agent to invoke correctly.

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, but the description adds value by stating that either 'nombre' or 'línea' must be provided and that no full listing is returned. This clarifies the relationship between the query and line parameters beyond their individual schema descriptions.

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 states a specific action ('Busca por nombre o línea'), identifies the exact resources (urban bus stops and Alicante TRAM stations), and lists the returned data (code, lines, coordinates). It also differentiates itself from the full-list case by stating that a name or line is required and no complete listing is returned.

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 ties this tool to a follow-up call to next_departures, making the intended workflow clear. It also explains the key limitation—no full list, name or line required—which helps an agent decide when this tool is appropriate.

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