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

Beyond the annotations (readOnlyHint, idempotentHint, etc.), the description adds crucial operational details: payment model ('pague por consulta com crédito pré-pago'), hosting context ('Hospedado pela plataforma, sem credenciais da plataforma'), data non-confidentiality ('não é dado sigiloso'), and LGPD compliance responsibilities. This exceeds annotation-only information.

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, well-structured paragraph that front-loads the core purpose and quickly moves to operational and legal notes. At ~50 words, it is concise but packs in multiple clauses. It could be slightly more scannable, but it remains effective.

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 read-only tool with no output schema, the description covers billing, data source, and legal accountability, which is helpful. However, it omits any parameter-level guidance or request construction details, which are critical for an API with three parameters and unclear combinations. It is adequate but has clear gaps.

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?

With 0% schema description coverage, the description needed to explain `cpf`, `cnpj`, and `birthdate`, but it does not mention them at all. There is no information about validation rules, optionality (none are required), or relationships (e.g., cpf vs cnpj). Users are left guessing parameter meaning, which is a significant gap.

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 ('consulta') and resource ('PGFN (CND Federal) - Segunda Via'). It specifies consultation of official Brazilian sources, distinguishing it from generic sibling tools like 'authenticate' and 'connect'. The scope is unambiguous.

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 implies usage for querying official tax data (e.g., 'consulta em fonte oficial') and notes practical conditions like payment and no credentials. However, it does not explicitly compare with alternatives or provide when-to-use/not-to-use guidance relative to other tools, though siblings appear functionally distinct.

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