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

With no annotations the description carries the full burden, and it does disclose meaningful traits: it is free, defaults to the current schedule (Europe/Madrid) when date is omitted, and explicitly does not fabricate openings when there is no coverage. It also names the data source and license. It omits rate limits, auth, and result format, so not a 5.

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?

Front-loaded with the core resource and filters, then the default behavior, then provenance. Two dense sentences with little waste, though the licensing/source sentence is not strictly needed for invocation.

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?

No output schema exists, so the description should describe return shape, but it does not. For a zero-required-param, read-style lookup tool it covers the main logic and the anti-hallucination guarantee, but leaves pagination (limit/offset) and result format unaddressed.

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 60%; the description explains the date/now interplay ('si se omite fecha') and the barrio/address meaning of area, matching schema intent. However limit and offset are documented in neither schema nor description, and the text adds no pagination or format detail, so it only partially compensates.

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?

States a specific resource (farmacias de guardia), scope (Madrid ciudad), and the two lookup keys (fecha or barrio). It is trivially distinguishable from all siblings, which are ITV/dataset tools, so an agent can select it purely from the name plus this line.

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?

Gives conditional behavior ('si se omite fecha, filtra el horario en curso') and cost ('Gratis'), which implies usage, but never states when to choose this over alternatives or any prerequisite/exclusion. Usage is only inferable, not explicit.

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