AI agents call consultar_cnpj to retrieve information from MCP Brasil API without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves publicly available information about a Brazilian company based on its CNPJ registration number. It performs a read-only query with no side effects. The blast radius of misuse is minimal—an attacker could only gather business information already in public registries. No data is created, modified, deleted, or financial operations are performed.
From the tool's definition Tool name 'consultar_cnpj' and description 'Obtém informações para um CNPJ brasileiro' (Obtains information for a Brazilian CNPJ) indicate a query/retrieval operation.
Documented attack patterns abuse exactly the kind of access consultar_cnpj gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Brasil API, and nothing reaches the server without passing your rules. This is the rule we recommend for consultar_cnpj:
{
"version": "1",
"default": "deny",
"tools": {
"consultar_cnpj": {}
}
}consultar_cnpj is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Obtém informações para um CNPJ brasileiro. It is categorised as a Read tool in the MCP Brasil API MCP Server, which means it retrieves data without modifying state.
Register the MCP Brasil API MCP server in PolicyLayer and add a rule for consultar_cnpj: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches MCP Brasil API. Nothing to install.
consultar_cnpj is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the consultar_cnpj rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for consultar_cnpj. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
consultar_cnpj is provided by the MCP Brasil API MCP server (lucianfialho/mcp-brasil-api). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP Brasil API, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
12 MCP Brasil API tools catalogued and risk-classified — across an index of 43,000+ MCP servers.