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

Annotations already declare readOnlyHint=true, indicating no side effects. The description adds behavioral context by specifying the computed outputs (total days lived, next birthday) beyond mere reading. This enriches the agent's understanding of what the tool returns.

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?

The description is two sentences, front-loaded with the primary purpose. Every word adds value; there is no redundancy or fluff. It is concise yet informative.

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?

Given the lack of an output schema, the description adequately outlines expected return values (years, months, days, total days, next birthday). It covers both input parameters implicitly. However, edge cases (e.g., invalid dates, future birth dates) are not addressed, which slightly limits completeness.

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%, with both parameters having clear descriptions in the schema (format and default). The description adds no additional parameter semantics beyond referencing 'fecha de nacimiento'. Baseline 3 is appropriate as the description does not enhance or expand on 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 uses a specific verb ('calcula') and clearly identifies the resource ('edad exacta en años, meses y días'), along with additional outputs. It distinguishes itself from sibling tools like calcular_diferencia_fechas by focusing specifically on age calculation from a birth date.

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 implies usage for calculating age from a birth date but provides no explicit guidance on when to use this tool versus alternatives (e.g., calcular_diferencia_fechas for date difference, convertir_edad_mascota for pet age). No exclusion criteria or alternative recommendations are given.

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