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

With no annotations, the description carries the burden of behavioral disclosure. It goes beyond a simple statement by listing included holidays (Carnaval, Sexta-feira Santa, etc.) and notes that facultativos can be optionally included. It also clarifies the default year behavior. However, it does not describe output format or mention the 'bancarios' parameter's effect (only banking holidays), which is a notable behavioral trait.

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 concise (three sentences) and front-loaded with the main action. It efficiently packs the scope, examples, optional behavior, and default handling without unnecessary filler. Every sentence contributes useful information.

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?

The tool has 3 optional parameters, no required parameters, no output schema, and no annotations. The description covers the main purpose, default behavior, and optional facultativos. However, it omits any mention of the 'bancarios' parameter, which is an important behavior (restricting to banking holidays) and could confuse users given the sibling tool 'feriados_bancarios'. This gap prevents a perfect completeness score, but overall the description is adequate.

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 well-described parameters for 'ano', 'bancarios', and 'facultativos'. The description adds minimal extra meaning beyond the schema, such as explicit examples of facultativos (Ponto Facultativo) and the default with omitted year. Since the schema already handles parameter semantics, the baseline 3 applies with only slight additions.

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 verb 'Lista' and the specific resource 'todos os feriados nacionais do Brasil para um ano específico', with a scope for year and optional filtering. It distinguishes from sibling tools by explicitly focusing on national holidays, which is unique among tools like feriados_por_cidade, feriados_por_estado, and feriados_bancarios.

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 provides clear context on when to use the tool: for listing national holidays of Brazil, with an optional inclusion of facultativos. It explains default behavior (if no year is provided, returns all available years) and mentions the optional 'facultativos' parameter. However, it does not explicitly mention alternatives or when not to use this tool, such as for state/city holidays, which are covered by siblings.

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