agent-payment-x402

Agent Payment Execution (x402)

Enable AI agents to make autonomous payments with built-in spending controls. Uses the x402 HTTP payment protocol and MCP tools so agents can pay for external services, APIs, or other agents without custodial risk.

When to Use

Use when: your agent needs to pay for an API call, purchase a service, settle with another agent, enforce per-task spending limits, or manage a non-custodial wallet. Pairs naturally with cost-aware-llm-pipeline and security-review skills.

How It Works

x402 Protocol

x402 extends HTTP 402 (Payment Required) into a machine-negotiable flow. When a server returns 402, the agent's payment tool automatically negotiates price, checks budget, signs a transaction, and retries — no human in the loop.

Spending Controls

Every payment tool call enforces a SpendingPolicy:

• Per-task budget — max spend for a single agent action
• Per-session budget — cumulative limit across an entire session
• Allowlisted recipients — restrict which addresses/services the agent can pay
• Rate limits — max transactions per minute/hour

Non-Custodial Wallets

Agents hold their own keys via ERC-4337 smart accounts. The orchestrator sets policy before delegation; the agent can only spend within bounds. No pooled funds, no custodial risk.

MCP Integration

The payment layer exposes standard MCP tools that slot into any Claude Code or agent harness setup.

Security note: Always pin the package version. This tool manages private keys — unpinned npx installs introduce supply-chain risk.

{
  "mcpServers": {
    "agentpay": {
      "command": "npx",
      "args": ["[email protected]"]
    }
  }
}

Available Tools (agent-callable)

Tool	Purpose
get_balance	Check agent wallet balance
send_payment	Send payment to address or ENS
check_spending	Query remaining budget
list_transactions	Audit trail of all payments

Note: Spending policy is set by the orchestrator before delegating to the agent — not by the agent itself. This prevents agents from escalating their own spending limits. Configure policy via set_policy in your orchestration layer or pre-task hook, never as an agent-callable tool.