days_between_dates

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states what the tool does but doesn't explain how it behaves—for example, whether it returns absolute values, handles date order, includes/excludes endpoints, or deals with errors. This leaves critical behavioral traits unspecified for a tool performing calculations.

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 a single, efficient phrase in Spanish ('Calcular días entre dos fechas') that directly conveys the tool's purpose without unnecessary words. It's front-loaded and appropriately sized for a simple calculation tool, with no wasted content.

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 tool's simplicity (2 parameters, no output schema, no annotations), the description is incomplete. It lacks details on output format (e.g., integer days), error handling, or behavioral nuances like date ordering. While concise, it doesn't provide enough context for reliable agent use without assumptions.

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?

The schema description coverage is 100%, with both parameters ('start_date' and 'end_date') clearly documented in the input schema regarding format (YYYY-MM-DD). The description doesn't add any additional semantic information beyond what the schema provides, such as explaining parameter interactions or constraints, so it meets the baseline for high schema coverage.

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 'Calcular días entre dos fechas' clearly states the purpose (calculate days between two dates) in Spanish, which matches the tool name. However, it doesn't differentiate from sibling tools like 'calculate_age' or 'format_timestamp' that also work with dates, and it lacks specificity about the calculation method (e.g., inclusive/exclusive, time zones).

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 provided on when to use this tool versus alternatives. There's no mention of sibling tools like 'calculate_age' or 'format_timestamp' that might handle related date operations, nor any context about prerequisites or limitations (e.g., date formats, handling of invalid inputs).

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