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

Beyond the readOnlyHint/openWorldHint annotations, the description reveals the on-demand official data source for bus stops, the fallback to estimated_eta labeled ESTIMATED when LIVE fails, and the explicit prohibition against using old cached arrivals as current state. This is valuable behavioral disclosure.

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?

Three dense sentences with no wasted words; the purpose is front-loaded and each sentence earns its place, including the essential fallback and data-freshness rule.

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 invocation, the description is complete: it gives the required parameter, source, and fallback behavior. However, with no output schema, it doesn't describe the returned structure for non-bus entity types (parking, beach, TRAM), which is a minor gap given the tool's multi-type scope.

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 meaning: it states that entity_id is exactly what resolve_entity returns and explains the bus-stop:<código> prefix behavior, going beyond the schema's basic identifier format.

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 verb and resource ('Estado ahora mismo de una entidad concreta ya identificada') and enumerates concrete entity types (parking, bus stop, TRAM, beach). It distinguishes itself from resolve_entity by explicitly requiring the entity_id that resolve_entity returns.

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?

It gives clear context: the tool must be used on an already-identified entity, and it specifies special handling for bus-stop codes. It does not, however, name sibling alternatives like next_departures or parking_availability or state explicit when-not conditions, so it stops short of a 5.

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