Comisiones y costos de venta

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

readOnlyHint=true already signals a safe read/compute operation, so the description need not restate safety. It adds that the output is a commission broken down by listing type, which is useful context, but it says nothing about whether all costs (shipping, fees) are included or what the result shape is.

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?

A single, front-loaded sentence with the core purpose stated first and the intended use appended cheaply. No filler, every clause carries meaning.

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?

There is no output schema, so the description should describe the return more fully; it names the returned quantity (commission by listing type) but omits the format and whether other costs are included. For a 4-parameter compute tool this is adequate but leaves the return underspecified.

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?

With 50% schema description coverage, the schema documents 'cuenta' and 'categoria' but leaves 'sitio' and the required 'precio' undocumented. The description hints that precio is the sale price and that a listing-type dimension affects the result, but adds no syntax or format detail beyond the schema.

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+resource: it tells you how much MercadoLibre charges in commission for selling at a given price. It even scopes the result (commission per listing type) and the intent (to compute margins). It's clear, though it doesn't explicitly differentiate itself from near-neighbors like ml_rentabilidad.

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 'para calcular márgenes' implies the usage context, so the agent can infer this is for margin/profit calculations. However, there is no explicit when-to-use/when-not guidance and no mention of alternatives such as ml_rentabilidad or ml_precio_catalogo.

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