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

With no annotations supplied, the description does add useful operational context: the data source (BCRA) and a cost of 1 credit, which the agent cannot infer from the schema. However, it says nothing about error/boundary behavior — e.g. what happens for a non-publication date, weekends/holidays, or whether the returned value may fall back to an earlier date — which matters for a read tool with zero annotation coverage.

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 that names the resource, the indices, the date default, the source, and the cost with no filler. The trailing 'Fuente' and 'Costo' fragments are terse and informative rather than wasteful.

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 simple 2-parameter tool with full schema coverage this covers the essentials, but with no output schema the description never indicates what the response looks like (numeric value, its currency/unit, the effective date of the returned value). That is a meaningful gap for a lookup tool whose output the agent must interpret.

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% and the enum already spells out the five index values; the description's expansions (ICL, IPC) and the 'último publicado' default duplicate what the schema's field descriptions already state. It adds brand recognition but no new parameter semantics, so the baseline 3 is correct.

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: 'Devuelve el valor de un índice económico argentino en una fecha', and enumerates the supported indices (UVA, CER, ICL, IPC mensual/interanual), so the agent knows exactly what it retrieves. It does not explicitly differentiate from siblings like convertir_uva or ajustar_monto, which keeps it from a 5.

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 implied by the resource description (fetch an index value for a date, or the latest if omitted), but there is no explicit when-to-use/when-not guidance and no pointer to convert_uva or the rental/adjustment tools for derived calculations. The default-date behavior is the only contextual hint.

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