MCP CNPJ Intelligence

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

With no annotations provided, the description carries full burden and does well by specifying what data is returned (detailed fields in 'RETORNA' section) and providing a concrete example. It doesn't mention rate limits, authentication requirements, or error conditions, but provides substantial behavioral context for a lookup tool.

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?

Excellent structure with clear sections (description, usage guidelines, returns, example). Every sentence earns its place - the purpose statement is front-loaded, usage guidelines are bulleted for clarity, returns are organized, and the example is specific and helpful. No wasted words.

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 single-parameter lookup tool with no output schema, the description provides comprehensive context: clear purpose, usage guidelines, detailed return values, and an example. It doesn't specify error cases or rate limits, but given the tool's simplicity and the detailed return specification, it's nearly complete.

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 100% description coverage with clear parameter documentation, so baseline is 3. The description adds value by providing a concrete example with Banco do Brasil's CNPJ, which helps users understand the expected format and provides a real-world reference point beyond the schema's technical specification.

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 specific verb ('busca' - searches) and resource ('dados cadastrais de uma empresa brasileira' - registration data of a Brazilian company) with the specific identifier ('pelo CNPJ' - by CNPJ). It explicitly distinguishes this tool from siblings like buscar_por_nome, buscar_por_cep, and buscar_avancado by focusing exclusively on CNPJ-based lookup.

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 'QUANDO USAR' section provides explicit guidance on when to use this tool: when you have a specific CNPJ, need to validate CNPJ existence/status, or want specific company details. This clearly differentiates it from alternative tools like buscar_por_nome (name-based search) or bulk_lookup (multiple records).

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