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

With no annotations, the description carries the full transparency burden. It discloses the source (Resolução 4.880/2020 do CMN), the included categories (national + facultative), and explicitly lists which facultative dates are covered (Carnaval, Quarta-feira de Cinzas, etc.). It also explains the effect of filtering by UF/IBGE. However, it does not mention default behavior when no filters or year are provided, or output format.

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 four sentences, each serving a clear purpose: core function, included dates, use case, and filtering capability. It is front-loaded and contains no filler, making it easy to scan.

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?

For a listing tool with 4 optional parameters and no output schema, the description provides a good overview: it explains the data source, coverage, and filtering options. It could be more complete by clarifying whether 'ano' is required or defaults to the current year, but the overall picture is solid.

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 each parameter already has a description. The tool description adds value by explaining the purpose of the UF/IBGE filters ('para incluir feriados bancários estaduais/municipais') and defining what 'facultativos' means in the context of the FEBRABAN calendar. This goes beyond the schema's basic field descriptions.

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's function with a specific verb ('Lista') and resource ('todos os feriados bancários do calendário oficial FEBRABAN'). It distinguishes from sibling tools by specifying 'bancários' and citing the official FEBRABAN resolution, making it clear this is the banking-specific holiday list, not generic holidays.

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 explicit usage context: 'Ideal para cálculos de vencimentos, compensações e prazos bancários.' It also explains when to use the filtering options ('Pode filtrar por estado...'). However, it does not explicitly name alternatives or state when not to use this tool, leaving some room for ambiguity among the sibling holiday tools.

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