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

With no annotations, the description carries the disclosure burden, and it does well: it states the tool returns tax, contributions, net yearly and monthly income, a recommended regime, and a full breakdown. There is no output schema, so this return-value detail is valuable. It does not claim side effects or permissions, which is acceptable for a computation tool, but adds no explicit statement of being a read-only calculation.

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 dense paragraph, front-loaded with the resource and scope, then the regimes, then outputs. It is long but every clause maps to a real capability of an 11-parameter tool, so little is wasted.

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 complex 11-parameter calculation tool with no output schema, the description successfully explains both the covered regimes and the returned values. The main missing piece is any explicit indication that this is a non-mutating estimate rather than a filing action, but overall it gives an agent enough to call it correctly.

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 100%, so the schema fully documents all 11 parameters (including the enum meanings for employment and region), making the baseline 3 appropriate. The description implies which inputs drive which regimes (e.g. arrival_year for Beckham) but adds no syntax or format detail beyond 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?

Specific verb (estimates/Оценивает) plus an exact resource and scope (Spain taxes for 2026), enumerating the regimes covered: IRPF general, all 17 autonomous communities plus País Vasco/Navarra, Beckham regime, IRNR non-resident, and Social Security/RETA contributions. This is unmistakably distinct from the DNV/translator siblings.

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 details the scenarios it handles (employee in/outside Spain, autónomo, Beckham-eligible via arrival_year), which implicitly signals when it applies, but it never states explicitly when to use it versus another tool or what inputs make it unsuitable. Usage is inferred rather than directed.

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