brasil-mcp-essentials

Official

by brasil-mcp

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Python

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validate_cpf

Validates Brazilian CPF numbers using the modulo 11 algorithm, rejecting repeated digit sequences.

Instructions

Valida CPF brasileiro (11 dígitos). Módulo 11. Rejeita sequências repetidas.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "value": "<value>"
    },
    "name": "validate_cpf"
  }
}

Input Schema

Name	Required	Description	Default
`value`	Yes

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.3.0Jul 30, 2026

TDQS

A4/5.0

Behavior4/5

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

With no annotations, the description carries the burden. It discloses the validation algorithm (Módulo 11) and rejection of repeated sequences, which are critical behaviors. However, it does not indicate whether input accepts formatted strings (e.g., with dots/dashes) or only digits, which is a minor gap.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is extremely concise: two short sentences covering the core purpose, algorithm, and a key rule. No fluff, every word adds value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's simplicity (one parameter, output schema existing), the description is fairly complete. It covers what the tool does and how it validates. Could mention edge cases or formatting, but overall sufficient for an AI agent.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The single parameter 'value' has 0% schema description coverage. The description adds that the input should be an 11-digit CPF, but doesn't clarify expected format (e.g., with/without punctuation) or provide details beyond the algorithm context.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states it validates Brazilian CPF, specifies length (11 digits), algorithm (Módulo 11), and rejection of repeated sequences. This is distinct from sibling tools like validate_cnpj or validate_pis, making 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.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage for CPF validation but provides no explicit guidance on when to use this tool versus alternatives (e.g., validate_cnpj for companies). No mention of prerequisites or when not to use.

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