X402 Buyer

The universal buyer agent for the x402 economy.

An MCP server that lets Claude Desktop, Cursor, and Claude Code users discover, pay for, and call any x402 endpoint — automatically. Ask Claude a question, and it pays for the answer with USDC.

No wallets. No crypto knowledge. No API keys. Just questions and answers.

What This Does

The x402 protocol lets AI agents pay for API calls with USDC. But until now, most tools in the ecosystem are sellers — endpoints that accept payment. This is the buyer — the agent that spends.

When you ask Claude "is stripe.com secure?" this MCP:

1. Discovers the right x402 endpoint (Domain Shield — VirusTotal + DNS security)
2. Pays $0.12 in USDC on Base via your AgentCash wallet
3. Returns the full scored security report to Claude
4. Claude synthesizes the answer naturally

You never touch a wallet. You never see a blockchain. You just get answers backed by premium data.

Install

Prerequisites

1. Fund an AgentCash wallet (one-time, 2 minutes):

   npx agentcash install
   

   Follow the prompts to create a wallet and fund it with USDC on Base. $5 covers ~40 calls.

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "x402-buyer": {
      "command": "npx",
      "args": ["-y", "x402-buyer-mcp"]
    }
  }
}

Cursor

Add to your .cursor/mcp.json:

{
  "mcpServers": {
    "x402-buyer": {
      "command": "npx",
      "args": ["-y", "x402-buyer-mcp"]
    }
  }
}

Claude Code

claude mcp add x402-buyer -- npx -y x402-buyer-mcp

Tools

x402_discover

Search for x402 endpoints that can answer a question.

"Find endpoints for domain security scanning"
"Search for company intelligence APIs"
"What x402 endpoints handle drug interactions?"

x402_call

Call any x402 endpoint with automatic payment.

"Call https://www.alderpost.co/api/domain-shield?domain=stripe.com"
"Call https://www.alderpost.co/api/company-xray?domain=hubspot.com"

x402_balance

Check your AgentCash wallet balance.

"What's my x402 balance?"
"How many calls can I afford?"

x402_research ⭐

The killer feature. Multi-endpoint parallel research. Give it a domain and it calls 3-5 endpoints simultaneously, returning a complete intelligence picture.

"Research stripe.com" → calls 5 endpoints (~$0.64):
  - Domain Shield (security scan)
  - Company X-Ray (firmographics)
  - Threat Pulse (threat intel)
  - Compliance Check (audit)
  - Prospect IQ (contact info)

"Research ibuprofen" → calls 1 endpoint (~$0.10):
  - Health Signal (FDA data + drug interactions)

"Research 123 Main St Milwaukee WI" → calls 1 endpoint (~$0.10):
  - Property Intel (demographics + amenities)

Budget control: set max_cost to cap total spend per research call.

Endpoints in Registry

The built-in registry includes premium endpoints backed by paid data sources:

Endpoint	What You Get	Price	Premium Source
Domain Shield	DNS security + malware scan	$0.12	VirusTotal (70+ engines)
Company X-Ray	Firmographics + tech stack	$0.15	People Data Labs
Threat Pulse	IP/domain threat intel	$0.10	VirusTotal + AbuseIPDB
Prospect IQ	Sales intel + email contacts	$0.12	Hunter.io
Compliance Check	IT compliance audit	$0.15	Qualys SSL Labs
Health Signal	Drug info + interactions	$0.10	NIH RxNorm + FDA
Property Intel	Location + demographics	$0.10	US Census + OpenWeather
Sports Edge	Pre-game AI analysis	$0.12	The Odds API + Claude AI

All endpoints powered by Alderpost Intelligence.

How Payment Works

You ask Claude a question
  → Claude calls x402_research or x402_call
    → This MCP calls AgentCash CLI
      → AgentCash signs a USDC payment on Base
        → The endpoint verifies + settles on-chain
          → Data returned to Claude
            → Claude answers your question

You fund AgentCash once. Every x402 call draws from that balance. No subscriptions. No API keys. Pay for exactly what you use.

Example Session

You: "Tell me everything about hubspot.com"

Claude: I'll run a comprehensive research scan on hubspot.com.
[Calls x402_research with subject "hubspot.com"]

Results from 5 endpoints ($0.64 total):

Domain Shield: Security score 85/100. DMARC=reject, SPF=pass,
DKIM configured. VirusTotal: clean (0/94 engines flagged).

Company X-Ray: HubSpot, Inc. Founded 2006. 10,268 employees.
Computer Software. Cambridge, MA. Public company.
Tech: Cloudflare CDN, Google Workspace, Next.js.

Threat Pulse: Threat score 92/100. No blacklist hits.
AbuseIPDB: 0 reports. Clean reputation.

Compliance Check: SSL Labs grade A. 6/6 security headers.
DNSSEC not enabled. Cookie consent detected.

Prospect IQ: Prospect score 82/100 (hot). 5 verified email
contacts found via Hunter.io. Email pattern: {first}@hubspot.com.

Pricing

This MCP server is free. You only pay for the x402 endpoints you call. Typical costs:

• Single endpoint call: $0.10 - $0.15
• Full domain research (5 endpoints): ~$0.64
• Health/property/sports query: ~$0.10

$5 in AgentCash covers approximately 40 individual calls or 8 full research reports.

Why This Exists

The x402 protocol is designed for agents to pay for data autonomously. But the ecosystem has a cold-start problem: sellers have built endpoints, but there aren't enough buyers calling them. This MCP is the buyer-side infrastructure that makes x402 work as intended.

Every install creates a new buyer in the x402 economy. Every research call generates 3-5 real on-chain transactions. This is how the agent economy bootstraps.

Links

• Alderpost Intelligence — Endpoint provider
• AgentCash — Wallet & payment infrastructure
• x402scan — Ecosystem explorer
• x402 Protocol — Protocol specification

License

MIT — Alderpost LLC, Wisconsin