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

With no annotations, the description carries the full burden. It does disclose two genuinely useful behavioral facts not in structured fields: the result is capped at a top 20 and the call costs USD 0.25, which matters for budgeting paid invocations. It omits any mention of authentication, rate limits, error behavior, or what fields each item contains.

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?

Three short sentences, each carrying distinct information: what is returned, accepted input forms, and cost. The core purpose is front-loaded and nothing is redundant or padded.

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?

The tool is simple (2 params, fully documented schema, no output schema, no annotations), and the description covers return size, input flexibility, and price. However, because there is no output schema, the description should say something about the shape of each best-seller entry; that gap leaves the agent unable to plan post-processing.

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 100%, so the schema already documents both parameters, including the country enum and the category ID-or-text example. The description repeats the same categoria examples (MLA1430, 'mates') without adding new semantics such as how free text is resolved to a category. Baseline 3 applies.

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 description states a specific verb and resource: 'Top 20 más vendidos de una categoría de Mercado Libre', which tells an agent exactly what is returned and its fixed size. It does not explicitly distinguish itself from siblings like precio_de_mercado or informe_oportunidad, but the purpose is unambiguous on its own.

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?

Usage is only implied: an agent infers it should call this when it wants best-seller rankings for a category. There is no explicit when-to-use vs when-not-to-use guidance and no mention of alternatives such as the pricing or report siblings, so routing must be inferred from the tool name and purpose.

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