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

Annotations already declare readOnly, idempotent and closed-world, so the safety profile is covered. The description adds genuinely useful domain caveats beyond that: capacities are informative and NOT summable across nodes, transformation centres and low voltage are excluded, and permitting goes through each node's operator. It stops short of describing result ordering or pagination behaviour.

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 tight paragraphs: the first front-loads what the tool returns and why, the second carries the data limitations. No filler, and the caveats are separated so they are easy to retain.

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 does enough by naming the returned entity (nodes with highest available capacity, max per bar) and the filters. It does not spell out the returned fields or ordering, which would help an agent interpret the ranking, but nothing essential for calling it correctly is missing.

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 coverage is 100%, so all five parameters are already documented, including that an empty provincia means all of Spain. The description reinforces the filter framing (province / operator / all Spain) and the 'máximo por barra' notion but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 (rank nodes by highest available capacity), the scope (a province, a grid operator, or all of Spain) and the data source (CNMC access-capacity maps). An agent immediately knows this is a ranking/locator tool rather than a detail lookup.

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?

Gives a clear use case: locate where there is headroom in the grid (for demand or generation) before searching for a site. It does not explicitly name the sibling tools (buscar_capacidad, detalle_nudo) or state when not to use it, so routing between siblings is left partly to inference.

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