refund_invoice · BTCPay Server MCP: Risk & Policy

WHAT IT DOES

What refund_invoice does on BTCPay Server MCP

AI agents use refund_invoice to commit financial operations through BTCPay Server MCP — usually the final step of a payment, billing, or trading workflow. A call moves real money.

WHY IT NEEDS A POLICY

Why refund_invoice needs a policy

Refunds move money back to customers and represent irreversible financial commitments. Although the description is empty, the tool name combined with the BTCPay financial context (payments, invoices) clearly indicates a financial operation.

From the tool's definition Tool name is 'refund_invoice' on a BTCPay Server MCP with financial operations (invoices, payments, pull payments). Refunds directly reverse financial transactions by returning funds to customers.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

refund_invoice Approval-gated

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

View as policy code

policy.json

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

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PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches BTCPay Server MCP, so you can run agents against it safely.

FAQ

Questions about refund_invoice

What does the refund_invoice tool do? +

refund_invoice. It is categorised as a Financial tool in the BTCPay Server MCP MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on refund_invoice? +

Register the BTCPay Server MCP server in PolicyLayer and add a rule for refund_invoice: 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 BTCPay Server MCP. Nothing to install.

What risk level is refund_invoice? +

refund_invoice 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 refund_invoice? +

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

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

refund_invoice is provided by the BTCPay Server MCP server (ThomsenDrake/btcpay-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.