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

The description adds significant behavioral context beyond the annotations: it discloses the hosting model ('Hospedado pela plataforma'), authentication requirements ('sem credenciais'), cost structure ('pague por consulta com crédito pré-pago'), data scope ('ACESSO PÚBLICO'), and legal responsibility (LGPD). These details help the agent understand operational and compliance aspects.

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 three sentences long, front-loads the core purpose, and includes necessary operational and legal context. It is slightly verbose with repeated emphasis on public access, but each sentence adds value and it remains easy to parse.

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 description covers key operational aspects: what it does, cost, auth, data privacy, and LGPD compliance. It does not describe return values, but there is no output schema and the tool is relatively simple. The annotations cover safety (read-only, idempotent), so the description adequately completes the picture for an agent to invoke the tool.

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 must compensate. It clearly explains the 'Chave' parameter (access key) implicitly. However, the 'completo' boolean parameter is not explicitly described; its meaning is only inferable from the tool name and 'dados completos'. This partial compensation warrants a mid-level score.

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: 'Consulta os dados completos de uma Nota Fiscal Eletrônica (NFe) a partir da chave de acesso' – a specific verb ('Consulta'), resource ('NFe'), and method ('a partir da chave de acesso'). It distinguishes itself from sibling tools by being a data query operation, unlike auth, marketplace, etc.

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 querying NFe data from an access key. It also notes important operational conditions (no credentials, prepaid credit) and the public nature of the data. It does not explicitly mention when not to use it or name alternatives, but the context is sufficient and there are no direct sibling alternatives.

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