x402_call

SERVERX402 Buyer SOURCE8randonpickart5/x402-buyer-mcp

Critical RISK CLASS

Category Financial

Parameters 00 required

Recommended Approval-gatedsee the rule below

Registry record Grade D, identity unverified Pull the record →

This record as markdown: /tools/8randonpickart5-x402-buyer-mcp/x402-call.md

WHAT IT DOES

What x402_call does on X402 Buyer

AI agents use x402_call to commit financial operations through X402 Buyer, usually the final step of a payment, billing, or trading workflow. A call moves real money.

RISK

Why x402_call is rated Critical

This tool autonomously initiates and completes real cryptocurrency (USDC) payments on the Base blockchain as part of its core operation. Every call to this tool can trigger an irreversible on-chain financial transaction. An AI agent misusing this tool (e.g., calling expensive endpoints repeatedly or with malicious URLs) could drain the funded wallet.

From the tool's definition automatic USDC payment via AgentCash, Signs USDC payment on Base via AgentCash wallet, Handles the complete x402 payment flow

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs x402_call safely

PolicyLayer is an MCP gateway: it sits between your AI agents and X402 Buyer, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For x402_call, this is the rule to start with:

x402_call Approval-gated

Any call to x402_call 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": {
    "x402_call": {
      "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 X402 Buyer, apply this rule, and every x402_call call is checked against it from then on.

FAQ

Questions about x402_call

What does the x402_call tool do? +

Call any x402 paid API endpoint with automatic USDC payment via AgentCash. Accepts a full URL with query parameters. Handles the complete x402 payment flow: 1. Sends request → receives 402 payment requirement 2. Signs USDC payment on Base via AgentCash wallet 3. Retries with payment proof → returns endpoint data Requires AgentCash wallet to be set up and funded (https://agentcash.dev). Examples: - url:. It is categorised as a Financial tool in the X402 Buyer MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on x402_call? +

Register the X402 Buyer MCP server in PolicyLayer and add a rule for x402_call: 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 X402 Buyer. Nothing to install.

What risk level is x402_call? +

x402_call 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 x402_call? +

Yes. Add a rate_limit block to the x402_call 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 x402_call completely? +

Set action: deny in the PolicyLayer policy for x402_call. 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 x402_call? +

x402_call is provided by the X402 Buyer MCP server (8randonpickart5/x402-buyer-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on X402 Buyer, and thousands of servers like it.

This server

All 4 X402 Buyer tools → Critical-risk tools on this server →

Across the catalogue

request_x402_payment on Pop Pay →fundos_create_capital_call on Fundos → All critical-risk MCP tools → The MCP Attack Database →

Guides

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