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

With no annotations, the description carries the full burden, and it does disclose the data source (public CSV) and absence of auth requirements, which implies a safe read-only lookup. It does not state behavior on invalid CNPJ input, whether results are cached/stale, or any rate/latency characteristics of reading the public file.

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?

Two short sentences with the core check front-loaded and the access precondition second; nothing is padded. Slightly under-specified rather than over-long, so conciseness itself is not a problem.

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?

An output schema exists, so return values need not be explained, and a single-parameter read tool is simple. Still missing the CNPJ input format and any differentiation from the CEIS sibling, both of which an agent needs to call the right tool correctly.

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?

Schema description coverage is 0%, so the description must compensate; naming the parameter as a CNPJ ties it to a Brazilian company registry number, which is more than the bare 'string' type conveys. It still omits the expected format (14 digits, punctuation allowed or not), which is the detail an agent most needs to build a valid call.

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?

States a specific verb and resource: checks whether a company (identified by CNPJ) appears as punished in the CNEP registry. The purpose is unambiguous, but it never mentions the sibling verificar_sancoes_ceis, which is a parallel sanctions registry an agent could easily confuse it with.

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?

Adds one useful operational cue — it reads from a public CSV and needs no API key — which tells the agent it can call it without credential setup. However, it gives no guidance on when to prefer CNEP over the CEIS sibling, nor what to do if the CNPJ is malformed or absent.

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