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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds value beyond them by disclosing the returned payload in detail (previous datapoint, up/down/flat trend, source, license, chart/history link), which matters since there is no output schema. Nothing about auth, rate limits, or empty-result behavior is stated.

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 leads with what the tool returns, then appends the payload fields. It is dense but earns its space given the absent output schema. The trailing field enumeration reads as a run-on and could be trimmed.

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 tool with no output schema, the description compensates by naming the returned fields, and it explains both identifier and text-search modes. Gaps remain around parameter combinations (e.g., `ambito` requiring `producto`, behavior with no arguments) and result limits, but an agent has enough 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 description coverage is 75%, with `serie`, `ambito` and `producto` documented inline; only `limite` lacks a description, though its default/min/max are in the schema. The description restates the identifier-vs-text distinction already in the schema but adds nothing about `ambito` scoping or `limite` behavior, so 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 concrete resource and scope: the last published price of a series (by identifier) or of products matching a text, and it enumerates what comes back (price, date, week, trend, source, license, link). An agent can tell it retrieves the latest datapoint rather than a series history. It never names its siblings (historico, buscar_producto), so differentiation is left to inference.

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?

It implies two operating modes — pass `serie` if you know the identifier, or match by `producto` text — which gives usable context. However, it never states when to prefer this over historico or buscar_producto, nor what happens if neither parameter is supplied. Usage is implied rather than prescribed.

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