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

With annotations covering the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), the description adds substantive domain behavior: the 35%/45% effort thresholds, 90%/70% financing by home type, and the 10% fallback for purchase costs when no comunidad is given. That exposes the calculation model rather than restating the annotations, though it does not disclose defaults for obra_nueva or plazo_anos.

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?

Three sentences, each earning its place: purpose/outputs first, then criteria, then the comunidad conditional. Dense but front-loaded and free of filler, with only minor strain from packing multiple thresholds into one sentence.

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?

Without an output schema the description correctly enumerates the three return values (max loan, max price, savings), which is its strongest completeness signal. It falls short by not explaining the effect of plazo_anos or obra_nueva and by giving no indication of result format, leaving gaps for a computation tool with eight parameters.

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 only 50%, so the description carries extra weight and does clarify how comunidad drives tax calculation and how tipo_vivienda switches financing between 90% and 70%. However, obra_nueva, plazo_anos, and the required ingresos_mensuales_netos receive no added explanation, leaving half the parameters without semantic guidance.

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 precise verb+resource (calculating borrowing capacity from net income and debts) and enumerates the concrete outputs: máximo préstamo, precio máximo de vivienda, ahorro necesario. It explicitly positions itself relative to the viabilidad sibling ('usa los mismos criterios que la viabilidad de la compra'), so an agent can separate it from mortar_calcular_cuota or mortgage_evaluar_viabilidad without opening schemas.

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?

The description explains the criteria that govern the calculation and gives a conditional rule about the comunidad autónoma, but it never states when to choose this tool over the sibling evaluar_viabilidad, calcular_cuota, or simular_primera_vivienda. Usage is implied rather than instructed.

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