refund_transaction

THE RISK

Critical Risk

Why refund_transaction needs a policy

This tool directly moves money by refunding financial transactions. It operates within a payment protocol system (AP2 — Agent-to-Agent Payment Protocol) and can reverse settled transactions either fully or partially. Misuse by an AI agent could result in unauthorized refunds, loss of revenue, or financial fraud.

From the tool's definition Tool explicitly performs 'Refund a settled transaction' with ability to specify refund amounts, indicating direct financial transaction reversal and money movement.

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

POLICY

How to control refund_transaction

PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp Ap2, and nothing reaches the server without passing your rules. This is the rule we recommend for refund_transaction:

policy.json

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

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

Create a free account and register Mcp Ap2 — 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

Related tools and policies

More Mcp Ap2 tools

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All 1300 Mcp Ap2 tools →

Financial tools on other servers

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Go deeper

Critical-risk tools in Mcp Ap2 → 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 refund_transaction

What does the refund_transaction tool do? +

Refund a settled transaction via refundTransaction. Amount defaults to the full settled amount when omitted. For partial refunds, pass a smaller amount. It is categorised as a Financial tool in the Mcp Ap2 MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on refund_transaction? +

Register the Mcp Ap2 MCP server in PolicyLayer and add a rule for refund_transaction: 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 Ap2. Nothing to install.

What risk level is refund_transaction? +

refund_transaction 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_transaction? +

Yes. Add a rate_limit block to the refund_transaction 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_transaction completely? +

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

refund_transaction is provided by the Mcp Ap2 MCP server (@codespar/mcp-ap2). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Mcp Ap2 tool call.

Start from Mcp Ap2, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →