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.
Part of the Agentpay server.
Free to start. No card required.
AI agents use fill_card to create or modify resources in Agentpay. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call fill_card repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Agentpay.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"fill_card": {
"limits": [
{
"counter": "fill_card_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Agentpay policy for all 17 tools.
These attack patterns abuse exactly the kind of access fill_card gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
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 Write tool in the Agentpay MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
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 Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
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.
Deterministic rules across all 17 Agentpay tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.