listar_empresas

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

Annotations are absent, so the description carries the full burden. It clearly states the tool is read-only (returns data, no side effects), free, and no key required. It also explains why the count is not hardcoded, adding behavioral context about dynamic data. This is more than a bare minimum.

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 well-structured with a clear opening sentence, then a list of outputs, usage context, and parameter/freemium info. It front-loads the core purpose and keeps sentences concise. The note about count is a bit extra but adds value.

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 zero-parameter tool with no output schema, the description is remarkably complete. It tells the agent what it returns, why it's useful, that it's free and keyless, and even points to 'saude' for dynamic count. An agent could call this tool without any further clarification.

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 zero parameters and 100% coverage (empty schema is fully covered). The description explicitly states 'Sem parâmetros', reinforcing the schema. Since there are no parameters to explain, the description adds value by confirming the absence, making the agent confident it needs no inputs.

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 lists Brazilian publicly traded companies covered by Dados B3, with specific fields returned (nome, CNPJ, código CVM, ticker principal) and total count. It distinguishes itself by being the starting point for finding tickers for other tools, differentiating from siblings like 'saude' or 'indicadores_anuais'.

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 explicitly states it has no parameters and is free without API key, and positions it as the entry point for discovering tickers. It does not explicitly mention when not to use it, but the context of being the starting point implies alternatives are for deeper analysis.

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