create_preference

THE RISK

Critical Risk

Why create_preference needs a policy

Creating a checkout preference in a payment processing context (like MercadoPago's Checkout Pro, commonly used with AFIP for invoicing) sets up a financial transaction flow. While it may not immediately move money, it creates a binding payment intent/preference that leads directly to financial commitment, placing it in the Financial category.

From the tool's definition "Create a checkout preference for Checkout Pro" — initiates a payment/checkout flow that commits financial obligations

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

POLICY

How to control create_preference

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 create_preference:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "create_preference": {
      "deny_if": [
        {
          "conditions": [],
          "on_deny": "Requires human approval."
        }
      ]
    }
  }
}

Any call to create_preference is blocked until a human approves it. The rest of the server keeps working.

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.

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EXPLORE

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Financial tools on other servers

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Go deeper

Critical-risk tools in Mcp Afip → Every critical-risk tool this server exposes, in one view.
All critical-risk MCP tools → Every critical-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Human-in-the-loop → When a tool call should wait for a person — and when policy can decide alone.
Tool call approval → Approval gates on individual tool calls: auto-allow, prompt, or deny.
How to Add Spending Controls to Any MCP Agent →
Rate Limiting MCP Tool Calls: A Practical Guide →

FAQ

Questions about create_preference

What does the create_preference tool do? +

Create a checkout preference for Checkout Pro. It is categorised as a Financial tool in the Mcp Afip MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on create_preference? +

Register the Mcp Afip MCP server in PolicyLayer and add a rule for create_preference: 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 create_preference? +

create_preference is a Financial tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit create_preference? +

Yes. Add a rate_limit block to the create_preference 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 create_preference completely? +

Set action: deny in the PolicyLayer policy for create_preference. 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 create_preference? +

create_preference 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.

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