pay_tab_open

Open a pre-funded metered tab with a provider. Use tabs for repeated API calls

SERVERPay Mcp SOURCE@pay-skill/mcp

Critical RISK CLASS

Category Financial

Parameters 00 required

Recommended Approval-gatedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-pay-skill-pay-mcp/pay-tab-open.md

WHAT IT DOES

What pay_tab_open does on Pay Mcp

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

RISK

Why pay_tab_open is rated Critical

This tool opens a pre-funded payment tab, which commits financial resources and establishes an obligation for future charges. Even though the actual charge occurs via sibling tools like 'pay_tab_charge', opening the tab is the critical financial gate that enables those charges. An AI agent tricked into calling this could establish unauthorized payment accounts.

From the tool's definition Tool name 'pay_tab_open' combined with server description 'USDC payments for AI agents on Base' and sibling tools 'pay_tab_charge', 'pay_tab_close', 'pay_send' indicate this tool opens a financial account/tab that enables subsequent charges.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs pay_tab_open safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Pay Mcp, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For pay_tab_open, this is the rule to start with:

pay_tab_open Approval-gated

Any call to pay_tab_open 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": {
    "pay_tab_open": {
      "deny_if": [
        {
          "conditions": [],
          "on_deny": "Requires human approval."
        }
      ]
    }
  }
}

GATE THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Pay Mcp, apply this rule, and every pay_tab_open call is checked against it from then on.

FAQ

Questions about pay_tab_open

What does the pay_tab_open tool do? +

Open a pre-funded metered tab with a provider. Use tabs for repeated API calls. It is categorised as a Financial tool in the Pay Mcp MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on pay_tab_open? +

Register the Pay MCP server in PolicyLayer and add a rule for pay_tab_open: 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 Pay Mcp. Nothing to install.

What risk level is pay_tab_open? +

pay_tab_open 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 pay_tab_open? +

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

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

pay_tab_open is provided by the Pay MCP server (@pay-skill/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on Pay, and thousands of servers like it.

This server

All 15 Pay tools → Critical-risk tools on this server →

Across the catalogue

pay_invoice on Bitcoin MCP Server → All critical-risk MCP tools → The MCP Attack Database →

Guides

Govern MCP payment tools →Human-in-the-loop →Tool call approval →