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

Annotations already declare readOnly, idempotent, and non-destructive, so the description adds valuable context: hosted on the platform, no platform credentials, pay-per-query with prepaid credits, and the data is public (not confidential). It also clarifies the client's data controller responsibility under LGPD, going beyond the raw annotations.

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, with a clear first clause stating the purpose, and subsequent clauses adding necessary context about cost, data source, and legal responsibilities. It avoids redundancy and is appropriately front-loaded, though the legal phrasing could be trimmed slightly.

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 one-parameter lookup, the description covers the data source, cost model, and safety profile sufficiently. However, it does not explain the return format or any input constraints (e.g., required length or formatting of the NFE identifier), which would be helpful given the lack of an output schema. It's 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?

The schema defines only one parameter 'nfe' as a string, but the description provides zero explanation of its format or meaning beyond the tool name. With 0% schema description coverage, the description should compensate, but it only says 'NFE' without specifying the expected identifier format (e.g., access key, number, length). This leaves ambiguity for the agent.

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 action (consultar/consult) on the resource (NFE from SEFAZ SC) and distinguishes it from the generic siblings like authenticate or show_version. It specifies it queries official Brazilian sources, setting it apart from typical CRUD tools.

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 retrieving official NFE data but does not explicitly state when to use it or when not to. It mentions the paid nature and LGPD compliance but lacks direct alternatives or exclusions. The context is sufficient for a simple lookup but not for decision-making among multiple tools.

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