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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false, and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful non-annotation context: it is free, uses reviewed public material, and will not supply design rules or unpublished prices. No contradiction with the annotations exists.

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?

The opening 'PRIMERA OPCIÓN, sin coste' is front-loaded and immediately actionable. The rest of the description is dense but purposeful: scope, content, limitations, and safety are each covered in a compact form. The 'para que la IA...' clause is slightly meta but still useful for an agent deciding when to invoke the tool.

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 read-only retrieval tool with a simple required enum, an optional filter, and a defaulted boolean, the description provides enough information to select and invoke it correctly. It specifies public scope, cost, content topics, and exclusions. The main missing detail is the exact return shape or pagination behavior, but that is minor given no output schema and the simple nature of the call.

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 67%, so filtro and incluir_metodo are already semantically documented. The description adds some context by linking tipo_de_agua to the document topics, but it does not explain the enum values ('consumo', 'residual', 'reutilizacion', 'aridos') or how to choose among them. This is adequate baseline behavior, not substantial compensation.

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 uses a specific verb ('Devuelve') and names the exact resource ('documentos públicos de Aguas SB') scoped by water type. It also positions the tool as 'PRIMERA OPCIÓN, sin coste' and 'Solo consulta', making its read-only knowledge-retrieval role clear. It stops short of a 5 because it never names a sibling tool as an alternative, so part of the differentiation is left to context.

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?

'PRIMERA OPCIÓN, sin coste' gives an explicit default selection rule, and 'sin reglas de diseño ni precios no publicados' draws a clear content boundary for when this tool is not the answer. It is strong contextual guidance, though it does not explicitly say which sibling to use instead in those excluded cases.

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