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

Annotations already establish readOnly/idempotent/non-destructive, and the description adds real value on top: it discloses the input length/format, what fields are decoded, and the important limitation that it cannot verify live vigencia because SENASA sits behind ARCA fiscal keys. That scope boundary is the kind of behavioral context annotations cannot convey.

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?

Front-loaded with the verb, resource and format before the caveats, and each sentence earns its place. The appended English translation is mildly redundant for an agent but does not harm routing.

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 well by listing the decoded segments (provincia, departamento, jurisdicción, establecimiento, productor). Combined with the format and the vigencia limitation, an agent has everything needed to call and interpret it.

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?

One parameter with 100% schema coverage, so baseline is 3. The description adds meaning beyond the schema by specifying the 17-character structure and format mask (00.000.0.00000.00), reinforcing the segment layout the schema's example only implies.

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 pair (valida/decodifica) and resource (código RENSPA), defines the resource, gives the exact format (17 caracteres, 00.000.0.00000.00), and enumerates the returned segments. No sibling tool overlaps with RENSPA decoding, so it is easily distinguished.

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?

Explicitly states a when-not: it does NOT check live validity ('NO consulta la vigencia en vivo') and routes the agent to the official public source for that purpose. Strong context, though it does not name a sibling tool alternative, so not a full 5.

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