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

Annotations already declare readOnlyHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds substantive domain behavior beyond that: 90% financing, a 35% effort ratio, and the rule that expenses use regional taxes when comunidad (and edad) is supplied and fall back to a 10% estimate otherwise.

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 dense sentences with the primary purpose front-loaded, followed by the key assumption (90% financing / 35% effort) and the tax-handling rule. No filler, though the tax sentence is somewhat compressed.

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 10-parameter tool with no output schema and only 50% schema coverage, the description covers the core intent and key assumptions but leaves the remaining inputs and the shape of the result unexplained, so it is only adequately complete.

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 50%, and the description clarifies the role of comunidad and edad (tax computation) and the financing/effort assumptions. However, several parameters (m2, ahorros, plazo_anos, ahorro_mensual, deudas_mensuales) remain undocumented in both the schema and the description, so the gap is only partly bridged.

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 goal: determine how much income and savings are needed to buy a first home and how many years it takes to accumulate the down payment. This clearly separates it from sibling calculators like mortgage_calcular_capacidad or mortgage_calcular_cuota, though it never names an alternative explicitly.

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 scenario (first-home purchase, young buyer via the edad/ITP mention) is implied and the community/age context hints at when it applies, but there is no explicit when-to-use guidance and no named alternative to route between this and the other mortgage_* tools.

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