Agent Search Pro — x402 Pay-Per-Call API + MCP Server

Live endpoint: https://aggregator-beta.vercel.app

Agent-native web search and research synthesis, paid per call in USDC on Base via x402. No buyer API keys, accounts, or subscriptions. Includes standard HTTP routes for x402 discovery plus a streamable HTTP MCP facade.

Experimental beta. Verified: the website, free API/MCP path, canonical 402 challenges, durable telemetry, and a controlled direct-transfer 0.02 USDC fulfillment test. On 2026-09-04 UTC, one operator-funded signed PAYMENT-SIGNATURE search purchase through XPay verify and settle was verified end to end: HTTP 402, signed EIP-3009 authorization, successful Base settlement, HTTP 200, and eight live results (search transaction). A second operator-funded signed synthesis purchase completed the same canonical flow for 0.10 USDC and returned three research angles with 15 live sources (synthesis transaction). This proves both paid routes work technically, but these tests are not external demand. There is no external paid demand or repeat buyer. See the public validation baseline and fixed decision rule.

Tiers

Tool	Price	What you get
web_search_sample	FREE	1 search, 3 results — no wallet needed
web_search	$0.02/call	Full search, up to 10 results (Serper)
web_synthesis	$0.10/call	Multi-angle research synthesis: core + latest + critique (3 parallel searches)

Try the live service in 10 seconds

No account, wallet, API key, or installation:

curl -s "https://aggregator-beta.vercel.app/api/sample?q=latest+AI+agent+payments"

The free route returns three live results. It is intentionally limited so agents can test output quality before deciding whether a paid call is worthwhile.

Connect as a remote MCP server

Use this exact Streamable HTTP endpoint in any MCP client that supports remote servers:

https://aggregator-beta.vercel.app/mcp

The MCP tools are web_search_sample (free), web_search ($0.02), and web_synthesis ($0.10). A raw JSON-RPC call looks like:

POST https://aggregator-beta.vercel.app/mcp
Content-Type: application/json

{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"web_search_sample","arguments":{"query":"x402 protocol"}}}

Paid calls return HTTP 402 with a canonical base64 PAYMENT-REQUIRED header (x402 V2). Compatible agent clients retry with PAYMENT-SIGNATURE; the public XPay facilitator verifies and settles EIP-3009 USDC directly from buyer to seller on Base.

Discovery surfaces

• GET /health — liveness + tiers
• GET /.well-known/x402.json — machine-readable payment manifest
• GET /llms.txt — LLM-readable service description

Run locally

MOCK_MODE=1 npm install && npm start   # full 402 flow, mock settlement — no keys
npm test                                # 16-check E2E suite

Production env

See .env.example. Requires: SERPER_API_KEY, PAY_TO_ADDRESS (Base wallet), and PUBLIC_URL. X402_FACILITATOR_URL optionally overrides the default public XPay facilitator. ALCHEMY_URL is only needed for the disabled-by-default manual tx-hash fallback.

Telemetry

Every interaction is emitted as structured [telemetry] JSON to platform logs. Production writes one immutable JSON event to a private Vercel Blob store; local development also appends telemetry/interactions.jsonl. Wallets are represented only by keyed, pseudonymous identifiers; raw wallet and transaction hashes are excluded.

Part of SuperSignal, an evidence-driven experiment in useful agent-native services.