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

Annotations already establish readOnly/idempotent/non-destructive, so the description only needs to add context, which it does: it discloses that comparison is restricted to intersecting months and that the summary reports first-to-last variation, plus relative variation when exactly two series are supplied. The instruction "El resumen es CALCULADO: decilo al usarlo" is a genuinely useful behavioral disclosure about the derived nature of the output, though return-format detail is partly redundant with the existing output schema.

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 front-loaded sentences: purpose and scenarios first, then return behavior, then the caveat about the computed summary. Nothing is padded, though the return-behavior clause overlaps with what the output schema already conveys.

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 rich annotations, 100% schema coverage, and an output schema, the description supplies exactly the missing pieces: the shared-month alignment rule and the computed-summary caveat. An agent can call this tool correctly without consulting anything else.

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 series syntax, enums of measure values, and the 'AAAA-MM' date format. The description adds only the semantic of intersecting months and the relative-variation rule tied to series count; it does not restate or extend parameter meanings beyond that.

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 ("Compara series mensuales en los meses que tienen en común") and enumerates concrete comparison scenarios (salarios vs inflación, canasta vs salarios, IPC por región, actividad vs precios), making the tool's scope unambiguous. It does not explicitly name which sibling to use for a single series (e.g. inflation_series, wages), so differentiation is inferred from the multi-series framing rather than stated.

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 use-case list gives clear context for when this tool is the right choice: cross-referencing two or more monthly series over their shared months. There is no explicit exclusion or pointer to alternatives for the single-series case, and the 2-to-4 series limit is only visible in the schema, not the description.

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