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. The description adds the computed outputs (new payment, savings, costs, payback period), which is useful since there is no output schema, but it says nothing about assumptions, rounding, or result limitations.

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?

A single sentence that front-loads the decision question ('si compensa cambiar') followed by the outputs. No waste; only slightly terse for a 6-parameter 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 calculator with no output schema, listing the return content is a reasonable substitute, and annotations carry the safety profile. However, the overlap with mortgage_calcular_cuota ('nueva cuota') is never resolved, and the undocumented parameters are left entirely to inference.

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 67% (tin_actual, tin_nuevo, gastos_cambio, meses_nuevo_plazo documented; capital_pendiente and meses_restantes undocumented). The description adds no parameter meaning whatsoever, so it fails to compensate for the two parameters left undocumented in the schema.

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 states a specific resource (cambio de hipoteca) and enumerates concrete outputs — nueva cuota, ahorro, gastos, and cuándo se recuperan — so an agent can distinguish it from a plain payment calculator. It does not, however, name or contrast with the many sibling mortgage tools (e.g. mortgage_calcular_cuota).

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?

'Si compensa cambiar la hipoteca de banco' strongly implies the usage scenario (evaluating a bank switch/refinance decision), which is better than nothing. But there is no explicit when-to-use versus alternatives, no prerequisites, and no exclusions, leaving routing to inference.

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