USE THIS to verify a Brazilian CPF (individual taxpayer ID) before relying on it — never assume 11 digits are valid. Checks the two mod-11 check digits and rejects all-identical sentinels. Call this for KYC/onboarding of Brazilian individuals.
| Name | Required | Description | Default |
|---|---|---|---|
| cpf | Yes | The CPF (11 digits; dots and dash are ignored). |
Changes observed during successful MCP inspections. Dates show when Glama detected each change.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, which the description aligns with. The description adds behavioral details beyond annotations: it verifies two mod-11 check digits and rejects all-identical sentinels, disclosing the validation logic and edge cases.
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 concise (three sentences) with a strong imperative opening. Every sentence adds distinct value: directive, validation logic, and typical use case. 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 validation tool with no output schema, the description fully covers purpose, validation algorithm, and common use case (KYC). It also addresses the specific sentinel rejection edge case, leaving no ambiguity about the tool's behavior.
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 provides basic description for the 'cpf' parameter (11 digits, ignored formatting). The description adds semantic value by explaining the validation algorithm (mod-11 checks, sentinel rejection), which is not in the schema and helps the agent understand what the tool does with the input.
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 uses specific verbs ('verify', 'checks') and clearly identifies the resource ('Brazilian CPF'). It explicitly mentions the two mod-11 check digits and rejection of all-identical sentinels, distinguishing it from many sibling validation tools for other countries.
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 'USE THIS to verify a Brazilian CPF before relying on it' and provides context like 'KYC/onboarding of Brazilian individuals.' It implies when-not-to-use by stating 'never assume 11 digits are valid,' but does not explicitly differentiate from similar tools like validate_cnpj for companies.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Each tool targets a specific identifier or operation (e.g., validate_iban, parse_date, is_holiday). Even similar tools like validate_isbn and validate_isbn10 are distinct by version. There is no overlap or ambiguity.
Most tools follow a verb_noun pattern (validate_xxx, parse_xxx, format_currency). The exception is 'next_holiday', which uses an adjective instead of a verb. Otherwise consistent.
With 47 tools, the set is very large. While each tool is distinct, the count exceeds the recommended range (25+ is considered too many) and may overwhelm users or agents.
Covers a wide array of international identifiers and utilities, but notable gaps exist (e.g., no Canada SIN, India PAN, Mexico CURP). The set is broad but not exhaustive for the domain of data validation.