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

Annotations already indicate readOnlyHint=true, idempotentHint=true, and destructiveHint=false, but the description adds meaningful behavioral context: it clarifies that the tool queries official public sources (non-sensitive data) and is hosted on the platform without platform credentials, requiring prepaid credit per query. It also contains LGPD data controller responsibilities, which are important for compliance. There is no contradiction with 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 and front-loads the core purpose, but it spends multiple sentences on legal and compliance disclaimers (LGPD, data controller) that are secondary to usability. While these add important context, they crowd out more critical operational details such as parameter guidance. The structure is functional but could be more focused.

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?

Given the tool's complexity (10 parameters, no output schema, no param guidance), the description is incomplete. It clarifies the data source and compliance aspects, but leaves the agent with no clear understanding of how to invoke the query (e.g., which credentials to supply, date formats, or the meaning of fields like codigo_receita). For a complex tool with zero schema descriptions, this is insufficient.

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 has 10 parameters, but schema description coverage is 0%, and the description provides no parameter-level details. The names (e.g., login_cpf, pkcs12_cert, codigo_receita) are opaque in Portuguese and lack any explanation of format, meaning, or relationships. This tool fails to compensate for the complete lack of schema description, offering no value beyond the raw parameter list.

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 purpose: to query payment receipts from the Brazilian Federal Revenue (Receita Federal) via an official source. It distinguishes itself from siblings by specifying the 'comprovante de pagamento' (payment receipt) use case and the formal/institutional nature of the tool, which is not evident in the sibling names.

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 implicitly conveys usage context by mentioning that it's a paid per-query service with prepaid credits and that it queries official Brazilian sources. However, it does not explicitly state when to use this tool over alternatives (e.g., other receipt or tax tools) or provide any exclusions. The absence of direct guidance on when not to use it and the lack of mention of alternative tools makes it only adequate.

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