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

Annotations already mark it read-only, and the description adds valuable context: hosted by the platform, no credentials required, public (non-confidential) data, and LGPD compliance responsibilities ('O cliente é o controlador dos dados'). This goes beyond the annotations to clarify data handling and legal implications.

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 run-on sentence that packs multiple facts (source, hosting, credentials, payment, data type, legal responsibility) without clear structure. It's not excessively long but could be better organized into clear points for readability.

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 simple read-only query tool, the description covers key aspects like data sensitivity and controller responsibility, but omits what the response will contain (e.g., refund status, invoice details) and potential error cases (e.g., invalid key, rate limits). It is minimally viable but leaves gaps for an agent needing to handle edge cases.

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?

The only parameter 'nfe' is completely undocumented in the schema (0% coverage) and the description does not clarify what format or value it expects (e.g., a 44-digit key, or invoice number). Since there is no description compensation, the agent is left guessing the exact input format.

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 identifies the tool as a query for NFE (Nota Fiscal Eletrônica) from SEFAZ SP, specifying the official source and the read-only nature ('consulta em fonte oficial'). It distinguishes itself enough from generic sibling tools, though it could be more explicit that 'nfe' is the invoice access key.

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 implicitly communicates usage context: no platform credentials needed ('sem credenciais da plataforma') and pay-per-query with prepaid credit ('pague por consulta com crédito pré-pago'). However, it does not explicitly state when to use this vs. alternatives or provide exclusions, leaving room for interpretation.

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