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

Even though annotations already mark the call as read-only/idempotent, the description adds real operational transparency: it names the official live endpoint, says the bus query always hits it on demand, and reveals the exact fallback (`estimated_eta`) with an explicit ESTIMATED label. This is exactly the kind of behavioral context annotations cannot convey.

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 purpose, preconditions, and bus-specific behavior are front-loaded in four dense sentences with no filler. The endpoint path is specific but earns its place by clarifying the authoritative source.

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?

With no output schema, the description doesn't describe the response shape or fields beyond mentioning `estimated_eta` in fallback. It also omits error/rate-limit behavior and how to resolve stop identifiers, so while it's adequate for invocation, it has clear completeness gaps.

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?

Input schema descriptions cover 100% of parameters, so the baseline is already solid. The description adds extra semantic meaning by mapping 'servicio' to mode and 'parada o destino' to stop/destination, and by explaining the live-vs-fallback behavior that affects how mode=bus results should be interpreted.

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 opening sentence names the resource ('servicio concreto de Alicante') and enumerates the five transport modes (bus, TRAM, Cercanías/ADIF, coach, C6), so an agent can tell this is a transit-query tool. It lacks an explicit main verb such as 'return' or 'get' and does not name sibling tools for differentiation, so it stops just short of top score.

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 states the precondition clearly: 'Requiere identificar el servicio y la parada o el destino' and explains mode=bus behavior. It does not mention when to prefer a sibling like find_transit_stop to obtain missing stop/destination codes or when to avoid the tool.

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