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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description adds valuable context about payment (prepaid credit), legal responsibilities (LGPD), and data confidentiality (not confidential). No contradictions with annotations, and it provides relevant behavioral details beyond the structured fields.

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 relatively short but packs in legal and payment information that could be streamlined. It is not front-loaded with the most critical usage instructions; the first sentence covers purpose, but subsequent sentences mix operational and compliance details. It is adequate 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?

For a simple read-only tool with one parameter, the description covers key aspects: official source, payment model, credentials, LGPD responsibilities, and data sensitivity. Annotations handle safety guarantees. It does not describe return format, but without an output schema, this is acceptable for a straightforward query 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?

The schema has only one parameter (cnpj) with zero description coverage. The tool description does not explain the format, purpose, or constraints of the cnpj parameter, relying entirely on the schema's basic string type. It 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 it queries official Brazilian sources (B3 participants) and distinguishes from sibling tools like authenticate, connect, and marketplace. The combination of tool name and description ("consulta em fonte oficial", "Consulta informação de fontes e órgãos oficiais brasileiros") makes the purpose unambiguous.

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 usage context by noting it requires prepaid credit, involves no platform credentials, and that the client is responsible for LGPD compliance. However, it does not explicitly state when NOT to use this tool or contrast it directly with alternatives, leaving some room for interpretation.

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