x402 Service Discovery MCP Server

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The community-built Bazaar for the x402 agentic economy — a continuously growing catalog of live services with real-time quality signals, facilitator-compatibility checks, and ERC-8004 trust scoring. The discovery layer that Coinbase's own PROJECT-IDEAS.md asked the community to build.

ScoutGate — Instant x402 API Monetization

Wrap any existing API in x402 payments in under 2 minutes — no protocol knowledge required

The x402 ecosystem's biggest friction point has been supply-side: getting an API behind x402 payments requires understanding EIP-712 headers, facilitator registration, and settlement logic. ScoutGate removes all of it.

# Register your existing API (30 seconds)
curl -X POST https://x402-scoutgate.onrender.com/register \  -H "Content-Type: application/json" \  -d '{"api_url": "https://your-api.com", "wallet_address": "0xYourWallet", "price_usd": 0.01, "name": "My API"}'
# Returns: {"proxy_url": "https://x402-scoutgate.onrender.com/api/abc123", "api_id": "abc123"}

That's it. Your API is now x402-enabled, auto-listed in x402Scout, and settling on Base mainnet in real USDC. ScoutGate handles facilitator integration, EIP-712 verification, and settlement.

Fee model: 2% per transaction (min $0.002). Live at: https://x402-scoutgate.onrender.com | Register your API

Terminal CLI — x402scout

Search the full x402 service catalog from your terminal

# Install (npm)
npm install -g x402scout

# Search
x402scout search "weather data"

# Top services by trust score
x402scout top 10

# Browse by category
x402scout browse data

# Scan a URL for x402 compliance
x402scout scan https://api.yourservice.com

# Ecosystem stats
x402scout stats

See cli/README.md for full usage.

scout_relay — Autonomous Payment Router

Route, execute, and audit x402 payments in a single call

Where the Discovery MCP finds what to call, scout_relay handles calling it — discovering the best service, making the x402 payment, retrying on failure, and returning the result. One call. Fully autonomous.

# Route an intent to the best matching x402 service
curl -X POST https://x402-scout-relay.onrender.com/route \
  -H "Content-Type: application/json" \
  -H "X-Payment: <your-x402-payment-header>" \
  -d '{"intent": "blockchain analytics for wallet 0xABC", "max_budget_usd": 0.05}'

4 MCP tools — add to any MCP client:

Fee model: max($0.003, 2.5% of downstream transaction value) per routed call.

Placement bids: Providers can register routing priority bids at POST /placement/bid (x402-gated, $0.01 registration fee). Bids are used as tiebreakers after trust-score filtering — merit first, always.

Live at: https://x402-scout-relay.onrender.com

What This Is (30 seconds)

x402 is Coinbase's HTTP-native micropayment standard for the agentic web. An AI agent hits an endpoint, gets an HTTP 402 challenge, pays with USDC on Base, and receives data — no API keys, no subscriptions, pure machine-to-machine.

The problem: Hundreds of x402-payable services exist across the ecosystem. The official x402.org catalog lists names. That's it. No uptime data. No latency scores. No facilitator-compatibility flags. No trust signals. An agent has no way to know which services are actually live, trustworthy, or compatible with its payment flow.

This MCP server solves it. Connect any Claude, Cursor, or Windsurf agent directly to the x402 Service Discovery API — a continuously-updated catalog with real quality signals on every entry. Find services, check health, verify facilitator compatibility, and register new endpoints — all from inside your AI workflow.

MCP Tools (5 discovery + 4 relay = 9 total)

Discovery Tools

Relay Tools (via scout_relay)

Quickstart — 30 Seconds to Discovery

Option A: Docker (recommended)

Add to your claude_desktop_config.json, Cursor MCP settings, or Windsurf config:

{
  "mcpServers": {
    "x402-discovery": {
      "command": "docker",
      "args": ["run", "-i", "--rm", "ghcr.io/rplryan/x402-discovery-mcp:latest"]
    }
  }
}

Option B: npx (no Docker required)

{
  "mcpServers": {
    "x402-discovery": {
      "command": "npx",
      "args": ["-y", "@rplryan/x402-discovery-mcp"]
    }
  }
}

Option C: Direct API

The Discovery API is publicly accessible — no authentication required:

# Search for services
curl "https://x402scout.com/discover?query=blockchain+analytics&max_price_usd=0.01"

# Full catalog
curl "https://x402scout.com/.well-known/x402-discovery"

Why This Matters

The Discovery Gap in x402

The x402 protocol solves payment. It does not solve discovery. When hundreds of services exist but agents can't find, evaluate, or route to them intelligently, the protocol's full value is unrealized.

This project fills that gap with three layers:

1. Discovery — Find x402 services by capability, category, price ceiling
2. Quality signals — Uptime %, latency (ms), facilitator compatibility, ERC-8004 trust score
3. Execution — scout_relay discovers, pays, retries, and returns results autonomously

What Makes This Different from x402.org/ecosystem

Live Catalog Stats

Total Services:      Live — check https://x402scout.com/catalog
Auto-scan interval:  6 hours
Scan sources:        x402.org/ecosystem, awesome-x402, GitHub search
Categories:          data, compute, agent, utility
Facilitator-compat:  Flagged per service
Trust signals:       ERC-8004 per service
Primary URL:         https://x402scout.com
Trust scores:        0-100 per service (ERC-8004 based)
Payment metadata:    x402Config (address, asset, version) per service
Router:              Live at https://x402-scout-relay.onrender.com

Catalog Sample

Example: Agent Workflow

Discovery only

# 1. Agent needs blockchain analytics under $0.01
result = x402_discover(
    query="blockchain analytics whale tracking",
    max_price_usd=0.01,
    category="data"
)
# Returns: ranked list with price, uptime %, latency, llm_usage_prompt

# 2. Scan for compliance + trust before paying
scan = x402_scan(url=result[0]["url"])

# 3. Check live health before committing
health = x402_health(url=result[0]["url"])

Full autonomous execution via scout_relay

# One call — discovery + payment + retry handled automatically
result = scout_route(
    intent="blockchain analytics for wallet 0xABC",
    max_budget_usd=0.05
)
# Returns: {result: {...}, provider: "...", fee_usd: 0.003, trust_score: 82}

Payments use EIP-712 signed TransferWithAuthorization via the x402 HTTP protocol — not direct ERC-20 transfer. Signature verified server-side; on-chain settlement via receiveWithAuthorization.

CDP Builder Grant Context

This project is a direct implementation of two items from Coinbase's own public roadmap:

From PROJECT-IDEAS.md in coinbase/x402:

"Dynamic Endpoint Shopper — An agent that discovers an MCP registry, pays for access, chains results from multiple services"

From the CDP x402 facilitator roadmap:

"A discovery layer for buyers (human and agents) to find available services (Bazaar)"

We built the community Bazaar. It's live. It has quality signals the official page doesn't. And it uses x402 payments itself — x402_discover costs $0.010 USDC, paid via the protocol it serves. scout_relay extends this: it routes and executes x402 payments autonomously, charging its own x402 fee for the service.

What We've Shipped (11 days)

Architecture

┌─────────────────────────────────────────────────────┐
│              AI Agent (Claude / Cursor / Windsurf)  │
│                                                     │
│  x402_discover → x402_health → x402_attest         │
│  x402_scan → x402_register → x402_health           │
│                                                     │
│  scout_route → scout_execute → scout_audit          │
└──────────┬──────────────────────────┬───────────────┘
           │ MCP (stdio/Docker)       │ REST / MCP
┌──────────▼──────────┐    ┌──────────▼──────────────┐
│  x402 Discovery     │    │  scout_relay v2.1.0      │
│  MCP Server         │    │  x402-scout-relay        │
│  ghcr.io/rplryan/   │    │  .onrender.com           │
│  x402-discovery-mcp │    │  Fee: max($0.003, 2.5%)  │
└──────────┬──────────┘    └──────────┬───────────────┘
           │ HTTPS                    │ HTTPS
           └──────────────┬───────────┘
                          │
┌─────────────────────────▼───────────────────────────┐
│     x402 Discovery API (Render, v3.7.0)             │
│     https://x402scout.com                          │
│                                                     │
│  • Growing catalog  • Auto-scan every 6h            │
│  • Health checks  • Facilitator compat flags        │
│  • ERC-8004 trust • llm_usage_prompt per service    │
└─────────────────────────────────────────────────────┘

Related Projects

Register Your Service

If you're building an x402-enabled service, add it to the catalog:

curl -X POST https://x402scout.com/register \
  -H "Content-Type: application/json" \
  -d '{
    "name": "My Service",
    "url": "https://myservice.example.com/api",
    "price_usd": 0.010,
    "category": "data",
    "description": "What your service does",
    "network": "base-mainnet"
  }'

Or use the x402_register MCP tool from inside Claude/Cursor/Windsurf.

Want routing priority? Register a placement bid at POST https://x402-scout-relay.onrender.com/placement/bid (x402-gated, $0.01 registration fee). Your service gets weighted as a tiebreaker after trust-score filtering — merit first, always.

License

MIT

Built on Coinbase x402 protocol | Base Network | ERC-8004 | Model Context Protocol