| name | agent-payment-x402 |
| description | Add x402 payment execution to AI agents with per-task budgets, spending controls, and non-custodial wallets. Supports Base through agentwallet-sdk and X Layer through OKX Payments / OKX Agent Payments Protocol. |
| origin | community |
Agent Payment Execution (x402)
Enable AI agents to make policy-gated 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.
Decision Tree
Choose the integration path based on whether your agent is buying access to a paid API or charging others for one:
| Need | Recommended path |
|---|
| Agent pays a 402-gated API on Base or another agentwallet-supported chain | Use agentwallet-sdk as an MCP payment server with strict spending policy |
| Agent pays a 402-gated API on X Layer | Use OKX Agent Payments Protocol from okx/onchainos-skills; okx-x402-payment is a deprecated legacy alias |
| TypeScript API charges agents | Use OKX Payments TypeScript seller SDK docs for Express, Hono, Fastify, or Next.js |
| Go API charges agents | Use OKX Payments Go seller SDK docs for Gin, Echo, or net/http |
| Rust API charges agents | Use OKX Payments Rust seller SDK docs for Axum |
| Java API charges agents | Use OKX Payments Java seller SDK docs for Spring Boot 2/3, Java EE, or Jakarta |
| Python API charges agents | Check the current OKX Payments repository before implementation; a Python seller guide may not be available |
Supported Networks
agentwallet-sdk: use the package docs to confirm current network coverage before production. Base Sepolia is the safest development default; Base mainnet is the production path called out by the original skill.- OKX Payments / X Layer: current seller docs target X Layer (
eip155:196) and USDT0 settlement. Fetch current SDK docs before generating production code because payment packages and facilitator behavior can change quickly.
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 negotiates price, checks budget, signs a transaction, and retries only inside the policy and confirmation boundary set by the orchestrator.
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.
Option A: agentwallet-sdk (Base / multi-chain)
{
"mcpServers": {
"agentpay": {
"command": "npx",
"args": ["agentwallet-sdk@6.0.0"]
}
}
}
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.
Option B: OKX Agent Payments Protocol (X Layer)
Use this path for X Layer x402, Multi-Party Payment (MPP), session payment, charge, and A2A charge flows.
For buyer-side agent flows:
- Install or reference the current
okx/onchainos-skills repository.
- Use
skills/okx-agent-payments-protocol/SKILL.md as the dispatcher.
- Treat
skills/okx-x402-payment/SKILL.md as a deprecated compatibility alias, not as the canonical skill.
- Require explicit user confirmation before wallet status checks or payment actions. Do not hide payment execution behind a generic tool call.
For seller-side API flows, fetch the latest language-specific guide before generating code:
| Runtime | Current guide |
|---|
| TypeScript | https://raw.githubusercontent.com/okx/payments/main/typescript/SELLER.md |
| Go | https://raw.githubusercontent.com/okx/payments/main/go/x402/SELLER.md |
| Rust | https://raw.githubusercontent.com/okx/payments/main/rust/x402/SELLER.md |
| Java | https://raw.githubusercontent.com/okx/payments/main/java/SELLER.md |
Do not copy examples from older docs without checking the current OKX repository. Current OKX guidance uses okx-agent-payments-protocol as the dispatcher, and Java seller docs are now available.
Examples
Budget enforcement in an MCP client
When building an orchestrator that calls the agentpay MCP server, enforce budgets before dispatching paid tool calls.
Prerequisites: Install the package before adding the MCP config — npx without -y will prompt for confirmation in non-interactive environments, causing the server to hang: npm install -g agentwallet-sdk@6.0.0
import { Client } from "@modelcontextprotocol/sdk/client/index.js";
import { StdioClientTransport } from "@modelcontextprotocol/sdk/client/stdio.js";
async function main() {
const walletKey = process.env.WALLET_PRIVATE_KEY;
if (!walletKey) {
throw new Error("WALLET_PRIVATE_KEY is not set — refusing to start payment server");
}
const transport = new StdioClientTransport({
command: "npx",
args: ["agentwallet-sdk@6.0.0"],
env: {
PATH: process.env.PATH ?? "",
NODE_ENV: process.env.NODE_ENV ?? "production",
WALLET_PRIVATE_KEY: walletKey,
},
});
const agentpay = new Client({ : , : });
agentpay.(transport);
policyResult = agentpay.({
: ,
: {
: ,
: ,
: [],
},
});
(policyResult.) {
(
);
}
(agentpay, );
}
(): <> {
(!.(apiCost) || apiCost < ) {
();
}
result;
{
result = agentpay.({ : });
} (err) {
();
}
(result.) {
(
);
}
: ;
{
parsed = .(
(result. <{ : }>)[].
);
(!.(parsed?.)) {
();
}
remaining = parsed.;
} (err) {
(
);
}
(remaining < apiCost) {
(
);
}
}
().( {
.(err);
process. = ;
});
Best Practices
- Set budgets before delegation: When spawning sub-agents, attach a SpendingPolicy via your orchestration layer. Never give an agent unlimited spend.
- Pin your dependencies: Always specify an exact version in your MCP config (e.g.,
agentwallet-sdk@6.0.0). Verify package integrity before deploying to production.
- Audit trails: Use
list_transactions in post-task hooks to log what was spent and why.
- Fail closed: If the payment tool is unreachable, block the paid action — don't fall back to unmetered access.
- Pair with security-review: Payment tools are high-privilege. Apply the same scrutiny as shell access.
- Test with testnets first: Use Base Sepolia for development; switch to Base mainnet for production.
Production Reference
