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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered upstream. The description adds a useful behavioral fact ('Gratis'), implying no purchase/permission barrier, but says nothing about the form or volume of the returned definitions.

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, front-loaded with what is defined and immediately followed by the free-access note. The bilingual gloss is minor redundancy but does not bloat the entry.

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 a simple, parameterless, read-only reference tool, the description covers purpose, scope of metrics, and cost. No output schema exists, but the enumerated metric list gives the agent enough to know what it will get.

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?

Zero parameters with a fully closed schema, so the baseline is 4. The description correctly implies a parameterless lookup and adds no param detail, which is appropriate here.

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 ('Definiciones de las métricas Lightning') and enumerates the metrics covered (Protagonismo IA, mención, orden, Top1, citación, HHI, etc.), so an agent knows this is a reference/lookup tool. It does not explicitly contrast with siblings like ver_ficha, but the naming is concrete enough to distinguish.

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?

'Gratis' hints that this reference is free and thus usable without purchase flow, which implicitly routes away from comprar_estudio, but there is no explicit when-to-use or when-not statement, and alternatives are not named.

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