void · Tabby MCP: Risk & Policy

WHAT IT DOES

What void does on Tabby

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

WHY IT NEEDS A POLICY

Why void needs a policy

Voiding an authorized payment is a financial operation that cancels a previously authorized transaction. This directly affects financial flows and payment obligations, making it a Financial category action. The blast radius is high because misuse could cancel legitimate authorized payments, disrupting the checkout/payment lifecycle for merchants and customers.

From the tool's definition 'Void an authorized payment' — voiding cancels an authorized payment transaction on the Tabby BNPL platform

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

void Approval-gated

Any call to void 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": {
    "void": {
      "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 Tabby, so you can run agents against it safely.

FAQ

Questions about void

What does the void tool do? +

Void an authorized payment. It is categorised as a Financial tool in the Tabby MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on void? +

Register the Tabby MCP server in PolicyLayer and add a rule for void: 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 Tabby. Nothing to install.

What risk level is void? +

void 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 void? +

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

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

void is provided by the Tabby MCP server (theyahia/tabby-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.