public_holidays

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

With no annotations, the description carries the burden and does disclose important behavioral caveats: default year is the current year, weekdays are included, Carnival is optional, and municipal holidays are excluded. It could say more about valid year ranges or read-only nature, but the behavioral context is solid for a simple lookup tool.

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 short, front-loaded, and every sentence adds useful scope information. The exclusions are clearly separated and no wording 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?

An output schema exists, so return values need not be explained. However, the description omits the upcoming_only parameter and any guidance on valid year ranges, which leaves a noticeable gap for a tool with 0% schema description coverage.

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 0%, so the description must compensate for both parameters. It clarifies the year parameter's default ('this year') but does not mention the upcoming_only parameter at all, leaving one of two parameters semantically undocumented.

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 that this returns Portugal's national public holidays for a year, including weekday, and distinguishes the scope from Carnival and municipal holidays. It is specific but does not explicitly contrast with a sibling tool, so 4 is appropriate.

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?

It gives useful scope guidance: Carnival is optional and municipal holidays are excluded, which helps an agent know when this tool is and is not appropriate. It stops short of naming an alternative or giving explicit when-to-use instructions, so it is not a 5.

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