Overview
AgentNDX exposes a REST API and an MCP endpoint at /mcp.
Some endpoints are free. Compute-heavy endpoints use the x402 protocol — pay per query in USDC on Base mainnet.
No accounts. No API keys. Bring a wallet.
Free Endpoints
GET /api/health System health check
GET /api/stats Total indexed, MCP count, A2A count, x402 count
GET /api/categories Category list with server counts
GET /api/services?category=&limit=&offset= Browse servers — free, paginated
GET /api/services/:id Basic server info — free
x402 Endpoints
These endpoints return 402 Payment Required on first call.
Pay via x402 protocol and retry with X-PAYMENT header.
GET /api/search?q=&limit=&category= Full search — semantic + keyword $0.005 USDC
GET /api/schema/:id Full tool schemas + deep analysis $0.05 USDC
GET /api/bulk?category=&limit= Bulk export — full dataset $0.10 USDC
MCP Endpoint
AgentNDX is itself an MCP server. Connect agents directly at https://agentndx.com/mcp.
JSON-RPC 2.0 over HTTP. Transport: http.
// MCP server config (claude_desktop_config.json or equivalent)
{
"mcpServers": {
"agentndx": {
"command": "npx",
"args": ["-y", "mcp-remote", "https://agentndx.com/mcp"]
}
}
}
TOOL search_services(query, protocols?, category?, limit?) $0.005 USDC
TOOL get_service(id) Basic free · full schemas x402 $0.05 USDC
TOOL list_categories() Free
TOOL get_stats() Free
Payment Flow
x402 is a standard HTTP payment flow. No accounts. No API keys. Just USDC on Base.
# Step 1: make request, get 402 back
GET /api/search?q=filesystem
HTTP/1.1 402 Payment Required
X-PAYMENT-REQUIRED: {"amount":"0.005","currency":"USDC","network":"base","recipient":"0x..."}
# Step 2: sign USDC payment on Base mainnet
# Step 3: retry with X-PAYMENT header
GET /api/search?q=filesystem
X-PAYMENT: <signed-payment-proof>
HTTP/1.1 200 OK
{ "results": [...] }
Use x402 client libraries for automated payment flows in your agent.
Rate Limits
Free endpoints: 60 requests/minute per IP.
Paid endpoints: no artificial limits — each payment is a separate transaction.
Abusive patterns (replay attacks, scraping at scale) will be blocked.