Generate a Stripe Checkout URL so the user can top up their OpenPrints pre-paid account balance. Present the returned URL to the user — they must open it in their browser to complete payment. Does not charge the card directly.
AI agents use topup_balance to commit financial operations through OpenPrints MCP — usually the final step of a payment, billing, or trading workflow. A call moves real money.
This tool initiates a financial transaction flow by generating a Stripe Checkout URL intended to add funds to a pre-paid account. Even though it does not charge the card directly, it creates a payment session that commits the user to a financial obligation upon completion. It falls squarely in the Financial category.
From the tool's definition 'top up their OpenPrints pre-paid account balance', 'Generate a Stripe Checkout URL', 'complete payment'
Attacks that exploit this kind of access
Generate a Stripe Checkout URL so the user can top up their OpenPrints pre-paid account balance. Present the returned URL to the user — they must open it in their browser to complete payment. Does not charge the card directly. It is categorised as a Financial tool in the OpenPrints MCP MCP Server, which means it involves financial transactions. Block by default and require explicit approval.
Register the OpenPrints MCP server in PolicyLayer and add a rule for topup_balance: 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 OpenPrints MCP. Nothing to install.
topup_balance 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 topup_balance 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 topup_balance. 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.
topup_balance is provided by the OpenPrints MCP server (openprints/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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