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

Annotations already declare readOnly/idempotent/non-destructive/open-world, so safety is covered. The description adds real non-obvious behavior: it is keyless (no auth needed), matching and field values are Spanish, and the returned payload shape is described (nregistro, flags, links to SmPC/leaflet).

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 purpose and scope before examples, and every sentence carries usable information. Slightly padded by example invocations that duplicate the schema examples array, preventing a perfect score.

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 carries the return-shape burden and does so concretely (registration number, substance, dosage, prescription/marketed/generic/orphan/biosimilar flags, document links). Combined with 100% parameter coverage and 5 params, an agent has everything needed to call it 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. The description earns above baseline by flagging the cross-cutting constraint that field values must be Spanish ('search paracetamol or ibuprofeno, not a US brand name') and by showing representative values per parameter, which the schema only partially conveys.

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 verb (Search) and a precisely scoped resource (AEMPS CIMA, the Spanish national medicine register), then enumerates the four lookup axes (name, ingredient, ATC, lab). It distinguishes itself from siblings like cima_medicine_detail and cima_changes_since by establishing the broad-search role.

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?

Frames the tool around concrete questions it answers ('is X authorised in Spain', 'which Spanish medicines contain ibuprofeno') and gives three worked invocations. It stops short of explicitly naming when to prefer cima_medicine_detail, but the query-to-tool mapping is clear.

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