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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is covered. The description adds valuable context: the data is not confidential, it is the same available to citizens, and the client is responsible for LGPD compliance. It also explains the payment mechanism (prepaid credits). These details go beyond the annotations and provide useful behavioral insight.

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 front-loaded with the core purpose ('SEFAZ ES: NFC-e, consulta em fonte oficial') and then adds practical details. It is a single paragraph of about 50 words, with no redundant filler. It is concise and well-structured, though the legal and payment notes could be trimmed without losing essential information.

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 one parameter, the description covers the data source and legal aspects but does not specify what the response contains or any required input format. Since there is no output schema, the description should at least hint at the expected return value (e.g., the NFC-e details). The absence of this information leaves a gap for the agent.

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 'nfce' is a string with zero schema description coverage. The description mentions 'NFC-e' in the purpose but does not explain the expected format (e.g., a key, a number, a URL). It gives a hint that the parameter is likely the NFC-e identifier, but this is not explicit enough for an agent to construct correct input. The description fails to compensate for the lack of schema documentation.

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 this tool consults NFC-e data from the official SEFAZ ES source. It uses the specific verb 'consulta' and identifies the resource (NFC-e), distinguishing it from sibling tools like authenticate or marketplace, which have different purposes.

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 context on when to use the tool (for NFC-e consultation from official sources) and mentions the payment model, but does not explicitly discuss alternatives or when not to use it. Since there are no closely related sibling tools, the absence of explicit exclusions is acceptable, but the guidance is not fully explicit.

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