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

No annotations, so the description carries the full burden. It does useful work by enumerating the returned payload (estado, montos, download links) in the absence of an output schema, but it never states that this is a read-only operation, what happens if the CUF is unknown, or any auth/rate-limit behavior.

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 states the lookup key first and then the payload. No filler and no redundancy.

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 single-parameter read lookup with no output schema, the description compensates by listing the return fields an agent can expect. It falls slightly short on error behavior (invalid or nonexistent CUF) and on the absence of an explicit read-only statement.

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?

Only one parameter (cuf) and the schema already describes it at 100% coverage as 'Código Único de Factura'. The description adds no format, length, or validation detail beyond what the schema provides, so it is a baseline 3.

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 (consultar/datos completos) and resource (factura), scoped by the CUF key and enumerating the returned fields (estado, montos, enlaces PDF/XML). It implicitly separates itself from listar_facturas by being a single-invoice lookup by CUF, but never names that sibling to make the distinction explicit.

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 only implied: the phrase 'por su CUF' signals you must already hold a CUF, and the field list hints at when this tool beats a listing. There is no explicit when-to-use/when-not guidance and no mention of listar_facturas or consultar_estado_siat as alternatives.

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