Tech Risk

Grey Ridge Signals — Agent-Native x402 Data & Security APIs

Pay-per-call crypto, DeFi, prediction-market, and on-chain data for AI agents — plus MCP security scanning — over the [x402 payment protocol](https://x402.org) on Base mainnet.

No account, no API key, no subscription. An agent pays inline in USDC (from $0.001/call) and gets the data back in the same request. Every data endpoint has a free preview so an agent can taste the payload before paying.

• Base URL: https://x402-data-api.sigrunner.workers.dev
• MCP endpoint (streamable-http): https://x402-data-api.sigrunner.workers.dev/mcp
• Canonical domain: https://x402-data-api.sigrunner.workers.dev (same API)
• Discovery: /.well-known/x402 · /openapi.json · /llms.txt
• Network: Base mainnet (eip155:8453), USDC. Settles via the non-custodial xpay facilitator — no Coinbase/CDP account needed. Also listed on the CDP x402 Bazaar.

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Two flagships — what agents actually pay for

1. MCP server security scan (/scan/mcp, $0.05) — a prompt-injection / tool-poisoning audit of an MCP server's tools (OWASP LLM01/LLM08). Zero-egress: for private/OAuth-gated servers you POST only the tools/list JSON — nothing else leaves your side. *There is no free equivalent for this* (unlike token-safety, where free multi-chain scanners exist). Free preview: POST /scan/mcp/preview. CI gate (on the GitHub Marketplace): uses: rezearcher/greyridge-x402-tools@v0.3.2.
2. Pre-trade decision gate (/gate/swap, $0.008 · /chain/token-report, $0.01) — a *decision* (GO/HOLD/BLOCK, SAFE/CAUTION/AVOID) sized to your trade, not raw flags your agent has to interpret. Base-native; if you trade other chains, keep your multi-chain scanner and use this on Base.

Everything below is the full catalog (crypto/DeFi data, on-chain reads, LLM, enrichment). Measured reliability at /status (not an SLA).

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Endpoints

Crypto & DeFi data

Base on-chain (JSON-RPC read primitives)

Base-native, multi-provider RPC with automatic failover (never fails a paid call on one provider's rate limit).

Agent trading gates (new)

Security

x402 payment verification (before and after your agent pays)

Free in MCP: x402_receipt_verify_preview (tx + payto, no payment).

Python agents, no key or wallet: uvx --from greyridge-x402-tools greyridge-x402-verify runs a local stdio MCP server (PyPI 0.6.0) with free x402_preflight and x402_receipt_verify tools. Add it to Claude Desktop/Cursor as command uvx, args --from greyridge-x402-tools greyridge-x402-verify.

Try it now, no key: curl "https://api.greyridgesignals.ai/x402/preflight/preview?url=https://api.greyridgesignals.ai/defi/yields" returns verdict: PAY, will_settle: true with the per-check detail (reachability, challenge, accepts, price accuracy, delivery).

Drop-in safe pay wrapper (free preflight, refuses AVOID, then dual-RPC receipt check on the settlement tx):

• Python: pip install greyridge-x402-tools (0.7.0), from greyridge_x402.safe_fetch import safe_fetch
• Node: npm install github:rezearcher/greyridge-x402-tools, import { safeFetch, PreflightBlocked } from "greyridge-x402-tools" (pass your own x402 fetch, e.g. wrapFetchWithPayment)

Already paying with @x402/fetch, wrapFetchWithPayment or a payer MCP such as Crypto APIs' x402_pay? Those pay and hand back the response body; none of them checks that the settlement tx actually moved the advertised amount to the advertised payTo. Keep your payer, and add the verify step after it: pass the tx hash from the X-PAYMENT-RESPONSE header and the URL you paid to x402_receipt_verify. It returns SETTLED, UNDERPAID, WRONG_RECIPIENT, NO_TRANSFER, REVERTED or NOT_FOUND. The x402 FAQ tells buyers to check the transaction themselves; this is that check, in one call.

How x402_receipt_verify differs from the read-only verifier @tensorfeed/x402-base-mcp (verify_x402_settlement, checked against its 0.2.1 README): theirs matches a Transfer against a recipient and amount the caller types in. Ours can pull payTo and amount from the endpoint's live 402 (?url=), so a wrong or stale expectation doesn't pass, and it compares two RPC providers and fails closed if they disagree. Theirs is a good fit if you just want generic Base reads (balances, eth_call) in the same server; ours only does verification.

Free previews: GET /crypto/prices/preview, /crypto/funding/preview, /defi/yields/preview, /chain/block-number/preview, /chain/gas-price/preview (full live data, not truncated), /scan/mcp/preview?url=. Zero-egress MCP scan (for private/OAuth-gated servers): POST /scan/mcp/preview with {"tools":[…]} is the free counts-only preview; POST /scan/mcp with the same body is the paid itemized scan — nothing leaves your side. One-liner: examples/mcp-scan-preview.sh.

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MCP server (the pull channel)

Add one remote MCP server and your agent gets the whole toolset. initialize and tools/list are free so agents can discover the tools; paid tools/call returns an x402 challenge.

tools/list advertises 22 tools: crypto_prices, crypto_funding, defi_yields, pm_markets, chain_block_number, chain_gas_price, chain_balance, chain_token_balance, chain_tx, chain_wallet, chain_token_security (paid Base RPC + data, EIP-7702 delegated-EOA aware), crypto_prices_preview, crypto_funding_preview, defi_yields_preview, pm_markets_preview, chain_block_number_preview, chain_gas_price_preview, chain_token_security_preview (free), and scan_mcp_server, scan_mcp_preview, enrich_tech_risk, enrich_domain (security).

// add to your MCP client config

{ "mcpServers": { "grey-ridge-x402": { "type": "streamable-http", "url": "https://x402-data-api.sigrunner.workers.dev/mcp" } } }

MCP client (mcp-client/ — the stdio companion)

For stdio-only MCP clients (Claude Desktop, Cursor, CLI agents), the repo ships a companion package, x402-data-api-mcp, in mcp-client/. It runs on the agent's own machine, speaks MCP over stdio, and proxies to the same Worker /mcp endpoint — it adds no data surface, just a transport + x402 payment shim so stdio-only clients can reach the same tools (22 tools, including paid ones when a wallet key is configured).

Install / run (local path). The package is not yet published to npm, so run it from the repo:

cd mcp-client

npm install npm run build # tsc → dist/server.js node dist/server.js # start (or: npm start)

Published path (one line, no clone): npx @grey-ridge/x402-data-api-mcp — the package is live on npm; its bin target is dist/server.js, so npx runs the same server.

Configuration. Copy mcp-client/.env.example to .env in mcp-client/: WORKER_BASE_URL defaults to the deployed Worker (set it only to point at your own mirror), and X402_WALLET_PRIVATE_KEY is optional — set it to auto-settle paid tools (HTTP 402) via x402; leave it empty to run only the free/preview tools. The client reads both straight from process.env at startup.

// stdio client config (local path)

{ "mcpServers": { "grey-ridge-x402-local": { "command": "node", "args": ["/absolute/path/to/mcp-client/dist/server.js"] } } }

Call it (HTTP)

BASE=https://x402-data-api.sigrunner.workers.dev

free preview — real sample, no payment

curl -s "$BASE/crypto/funding/preview"

paid — returns HTTP 402 with an x402 payment-required challenge until you attach payment

curl -i "$BASE/crypto/funding?limit=10"

Any x402-capable client (e.g. the x402 libraries) handles the 402 → sign → retry automatically.

Measured status

Uptime and latency per safety route are measured from a probe cron and published in docs/STATUS.md (regenerated hourly; window