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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the bar is lower; the description nonetheless adds real context: the index source by code, the fact it is free and uncapped, the currency and period granularity of the answer, and fallback behavior when a parameter is absent. It does not describe response shape in detail, but the added behavioral traits are substantive.

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?

It is front-loaded with a concrete user question that anchors the use case, followed by method, units, and parameter behavior in a compact sequence. The [EN] translation and the explicit 'Params:' enumeration duplicate what follows in the schema, costing a little economy, but overall it is dense rather than 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?

With no output schema, the description carries the return-value burden and does so: it specifies annual and monthly figures, ARS and USD, exact canon versus scenarios, and names the official index used. The only remaining ambiguity an agent must resolve is the overlap with the closely named sibling tool.

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 coverage is 100%, so the baseline is 3; the description earns one more by explaining the consequence of each optional parameter — kg_ha_anio switches from exact canon to 40–100 kg/ha/year scenarios — which sharpens what the schema only sketches ('se responden escenarios'). The restated param list is redundant but the scenario range adds genuine meaning.

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 verb and resource — valuing farmland rent against the official MAG index (haciinfo000013) — with concrete output units (ARS/USD, annual/monthly). It is clear on its own, but it never differentiates itself from the sibling 'calculate_farmland_rent', which sounds functionally identical, nor from 'value_farmland' (land value vs. rent).

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 gives an explicit branch condition: providing kg_ha_anio yields the exact canon, omitting it returns 40–100 kg/ha/year scenarios. That is clear usage context. However, there are no exclusions or sibling routing (e.g., when to prefer 'calculate_farmland_rent' or 'value_farmland' instead), so the guidance stops short of the top band.

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