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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. 'Sin clave' adds genuine value beyond the schema by signalling no API key/auth is needed. However, nothing is said about the time horizon of 'próximos plazos', result shape, or pagination.

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?

Two compact clauses with no filler and the subject front-loaded. It is close to under-specification rather than exemplary conciseness, but no sentence is wasted.

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 burden of explaining what comes back, and it does not: the meaning of 'Modelos' and the horizon of 'próximos plazos' are undefined. For a data-returning lookup tool, an agent lacks enough to predict or use the response.

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 0% for two parameters, so the description must compensate. It does so partially by tying the input to an IAE/CNAE code, which clarifies the meaning of the enum in code_type. It says nothing about the required format of 'code' (the schema allows digits and dots), leaving a real gap.

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 the resource precisely: 'Modelos AEAT y próximos plazos' (AEAT forms and upcoming deadlines) scoped to a given IAE/CNAE code. An agent can distinguish it from siblings like detalle_iae or detalle_cnae, which return code details rather than tax deadlines. The verb is only implicit (a lookup), so it stops short of 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?

There is no statement of when to use this tool instead of alternatives such as obligaciones_fiscales or buscar_codigo. The only usage-adjacent hint is 'Sin clave', which speaks to authentication, not tool selection.

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