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

Annotations provide readOnlyHint=true, meaning the tool is a pure computation with no side effects. The description adds that it 'knows' habitual percentages by country, which is useful behavioral context, but does not elaborate on other behavioral aspects (e.g., default behavior when porcentaje is omitted). No contradiction with annotations.

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 extremely concise: two sentences that front-load the core function (calculate tip and split) and add a secondary feature (country knowledge). Every sentence adds value with no redundancy or fluff.

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 low complexity and complete parameter schema, the description covers the essential purpose and a notable feature (country defaults). However, it does not mention that users can override the percentage or that splitting is optional, but these are conveyed by the schema and default values. Overall, it is sufficiently complete for a straightforward calculator tool.

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%, so the baseline is 3. The description mentions country-specific percentages, which adds minimal context beyond the schema's description of the 'pais' parameter. It does not explain the 'porcentaje' or 'personas' parameters beyond what the schema already provides.

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 clearly states the tool calculates restaurant tips and splits bills, using a specific verb ('calcula') and resource ('propina'). It distinguishes itself from sibling calculation tools by focusing on a specific domain (restaurant tips with country-specific percentages).

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?

No guidance is given on when to use this tool versus alternatives like 'calcular_porcentaje' or other calculators. The description implies usage for tip calculation but does not provide explicit when/not-to-use criteria or mention alternative tools.

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