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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the bar is lowered. The description adds genuinely new operational context: no API key is required ('Sin clave') and results carry a canonical page URL. It does not discuss rate limits, result quality, or how the semantic match is scored, but for a read-only search this is solid.

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?

Two compact sentences with the core capability front-loaded and the return-value note following. Nothing is padded, though the parenthetical '(búsqueda semántica)' and the '(url)' gloss are slightly redundant.

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 usefully names one return field ('url'), but it omits the remaining result fields and leaves three of four input parameters undocumented. For a 4-parameter search tool with zero schema coverage, this is not enough for an agent to invoke it confidently across the type/top_k/threshold options.

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 description coverage is 0% and there are 4 parameters, so the description carries the full burden but only obliquely covers 'q' via 'por descripción'. The enum values for 'type' (iae, cnae, cnae_2009, modelos, all), plus 'top_k' and 'threshold', are never explained, leaving the agent to guess what 'modelos' or 'all' mean or how threshold affects results.

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 and resource ('Busca códigos IAE/CNAE por descripción') and identifies the retrieval mode as semantic, which is meaningfully different from exact-code lookup tools. It does not name siblings such as detalle_iae, detalle_cnae or empresas_por_actividad, so the agent must infer the boundary itself.

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 phrase 'por descripción (búsqueda semántica)' implies the tool is for fuzzy/natural-language discovery rather than exact code lookup, which is a usable usage signal. However, there is no explicit when-to-use, when-not-to-use, or named alternative among the many sibling code tools, so routing remains partially inferred.

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