fill_card
Fill only the card fields on a checkout page with an existing card. Use when you already have a card ID and want to handle the rest yourself. The card number is sent directly to the browser — you never see it.
This record as markdown: /tools/agentpay/fill-card.md
What fill_card does on Agentpay
AI agents invoke fill_card to trigger actions in Agentpay. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.
| Parameter | Type | Required | Description |
|---|---|---|---|
card_id | string | Yes | Card ID to fill |
Parameters from the server's own tool schema.
Why fill_card is rated High
This tool performs browser automation (filling card fields on a checkout page), which is an Execute-category action. It triggers external operations by injecting payment card data into a browser form.
From the tool's definition Fill only the card fields on a checkout page with an existing card... The card number is sent directly to the browser
Attacks that exploit this kind of access
The rule that runs fill_card safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Agentpay, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For fill_card, this is the rule to start with:
fill_card stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Agentpay, apply this rule, and every fill_card call is checked against it from then on.
Questions about fill_card
Fill only the card fields on a checkout page with an existing card. Use when you already have a card ID and want to handle the rest yourself. The card number is sent directly to the browser — you never see it. It is categorised as a Execute tool in the Agentpay MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
fill_card accepts 1 parameter: card_id. Required: card_id. The full parameter table on this page comes from the server's own tool schema.
Register the Agentpay MCP server in PolicyLayer and add a rule for fill_card: 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 Agentpay. Nothing to install.
fill_card is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the fill_card 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 fill_card. 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.
fill_card is provided by the Agentpay MCP server (agentpay-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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