Permanently store a tokenized payment method in the Braintree vault via vaultPaymentMethod. The input paymentMethodId must be a single-use nonce; the mutation returns a permanent vaulted payment method id that can be reused for future charges.
AI agents use vault_payment_method to commit financial operations through Mcp Ap2 — usually the final step of a payment, billing, or trading workflow. A call moves real money.
This tool stores a payment method in a financial vault (Braintree), enabling future charges. It directly interacts with payment infrastructure — storing credentials that can be used to initiate financial transactions. Misuse could lead to unauthorized storage of payment methods and subsequent fraudulent charges, placing it firmly in the Financial category with high severity.
From the tool's definition 'Permanently store a tokenized payment method in the Braintree vault', 'mutation returns a permanent vaulted payment method id that can be reused for future charges'
Documented attack patterns abuse exactly the kind of access vault_payment_method gives an agent:
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 vault_payment_method:
{
"version": "1",
"default": "deny",
"tools": {
"vault_payment_method": {
"deny_if": [
{
"conditions": [],
"on_deny": "Requires human approval."
}
]
}
}
}Any call to vault_payment_method is blocked until a human approves it. The rest of the server keeps working.
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Permanently store a tokenized payment method in the Braintree vault via vaultPaymentMethod. The input paymentMethodId must be a single-use nonce; the mutation returns a permanent vaulted payment method id that can be reused for future charges. 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.
Register the Mcp Ap2 MCP server in PolicyLayer and add a rule for vault_payment_method: 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.
vault_payment_method is a Financial tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the vault_payment_method 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.
Set action: deny in the PolicyLayer policy for vault_payment_method. 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.
vault_payment_method 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.
Start from Mcp Ap2, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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1300 Mcp Ap2 tools catalogued and risk-classified — across an index of 43,000+ MCP servers.