list_variables

THE RISK

Low Risk

Why list_variables needs a policy

This tool retrieves metadata about monetary variables from the AFIP system for discovery purposes. It does not create, modify, delete, or execute any operations — it simply returns a catalog of existing variables. The low severity reflects minimal blast radius: misuse would only result in an AI agent viewing available variable information without the ability to modify financial data or trigger transactions.

From the tool's definition Tool description states 'List the catalog of monetary variables' — a retrieval operation with no side effects. The verb 'list' and the purpose ('discover variable ids') confirm read-only behavior.

Documented attack patterns abuse exactly the kind of access list_variables gives an agent:

POLICY

How to control list_variables

PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp Afip, and nothing reaches the server without passing your rules. This is the rule we recommend for list_variables:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "list_variables": {}
  }
}

list_variables is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Mcp Afip — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

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EXPLORE

Related tools and policies

More Mcp Afip tools

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about list_variables

What does the list_variables tool do? +

List the catalog of monetary variables (id, descripción, categoría) — use this to discover variable ids for get_variable_history. It is categorised as a Read tool in the Mcp Afip MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list_variables? +

Register the Mcp Afip MCP server in PolicyLayer and add a rule for list_variables: 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 Afip. Nothing to install.

What risk level is list_variables? +

list_variables is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit list_variables? +

Yes. Add a rate_limit block to the list_variables 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.

How do I block list_variables completely? +

Set action: deny in the PolicyLayer policy for list_variables. 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.

What MCP server provides list_variables? +

list_variables is provided by the Mcp Afip MCP server (codespar/mcp-dev-latam). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Mcp Afip tool call.

Start from Mcp Afip, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →