MCP server de Grey Ridge Signals

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 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

Endpoint	Price	Returns
GET /crypto/prices?coins=bitcoin,ethereum,solana	$0.001	Spot token prices (DefiLlama), keyless. Up to 25 CoinGecko ids.
GET /crypto/funding?limit=20	$0.001	Cross-venue perp funding rates (Hyperliquid + OKX, graceful fallback) with the funding spread + best long/short venue — the arb signal, not just a single-venue list.
GET /defi/yields?limit=20&project=&chain=&stable=	$0.001	Top DeFi lending/LP yields (DefiLlama) with APY breakdown, 7d/30d APY trend, IL risk, and DefiLlama's stability forecast — decision-grade, not a raw list.
GET /pm/markets?query=&limit=20	$0.005	Live Polymarket prediction markets: question, outcomes, prices, volume, liquidity, end date.

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).

Endpoint	Price	Returns
GET /chain/block-number	$0.001	Current Base block number
GET /chain/gas-price	$0.001	Current gas price (wei + gwei)
GET /chain/balance?address=	$0.001	Native ETH balance
GET /chain/token-balance?address=&token=	$0.001	ERC-20 token balance
GET /chain/tx?hash=	$0.001	Transaction details
GET /chain/receipt?hash=	$0.001	Transaction receipt (status, gas used, logs)
GET /chain/code?address=	$0.001	Contract-code check — is it a contract, and EIP-7702 delegated-EOA detection (is_eip7702_delegate / delegate_address)
GET /chain/wallet?address=	$0.003	Bundle: ETH balance + tx count + contract flag in one call, EIP-7702 delegated-EOA aware (is_eip7702_delegate / delegate_address)

Agent trading gates (new)

Endpoint	Price	Returns
GET /gate/swap?token=0x…&side=buy|sell&notional_usd=N	$0.008	Pre-trade go/hold/block decision for any Base ERC-20: safety verdict, risk score, pool liquidity and price-impact of your size, flags. One call before an agent swaps. Free live sample: /gate/swap/preview
GET /chain/token-report?token=0x…	see /openapi.json	Full token due-diligence report (security + liquidity + metadata) in one call

Security

Endpoint	Price	Returns
GET /scan/mcp?url=	$0.05	Security audit of a target MCP server: tool-poisoning / prompt-injection / exfiltration / dangerous-capability / hidden-unicode (OWASP LLM01/LLM08) + risk score
POST /scan/mcp {"tools":[…]}	$0.05	Zero-egress audit — paste your own tools/list array; same itemized findings, nothing leaves your side and we never fetch/call your server. For OAuth-gated or private MCP servers that won't expose a URL
GET /enrich/tech-risk?domain=	$0.05	Tech-stack fingerprint → CVE (NVD) + EPSS + CISA-KEV attack-surface risk
GET /enrich/domain?domain=	$0.01	Firmographic + tech-stack enrichment, incl. full subdomain enumeration (subdomains[]) via crt.sh certificate-transparency logs, RDAP, DoH, HTTP fingerprint

x402 payment verification (before and after your agent pays)

Endpoint	Price	Returns
GET /x402/preflight?url=	$0.001	Pre-pay check on any x402 endpoint: will it settle, is the payee safe (OFAC / scam lists), price accuracy, delivery readiness, liveness → PAY / CAUTION / AVOID
GET /x402/receipt-verify?tx=&url=	$0.004	Post-pay proof: reads the Base settlement tx from two independent RPCs and reconciles the USDC Transfer against the endpoint's own live 402 (payTo + amount) → SETTLED / UNDERPAID / WRONG_RECIPIENT / NO_TRANSFER / REVERTED / NOT_FOUND / UNVERIFIED

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 stated in the file, not an SLA).

How it runs

A single Cloudflare Worker implements every HTTP endpoint and the MCP server behind a method-aware x402 gate. All upstreams are free/keyless public APIs (DefiLlama, Hyperliquid, OKX, Polymarket Gamma, Base JSON-RPC, NVD/EPSS/CISA-KEV, crt.sh/RDAP/DoH); every address/hash/domain input is validated and SSRF-guarded (fixed upstream hosts, no user-supplied targets except the explicitly-scoped /scan/mcp and enrichment endpoints).

License

MIT — see LICENSE.

Agent-framework plugins (published)

Pre-trade token guard (/gate/swap, $0.008 USDC via x402 on Base) — drop-in, fails closed, pays inline per call (no API key, no account). Free sample: curl "https://x402-data-api.sigrunner.workers.dev/gate/swap/preview?token=degen"

Framework	Install	Source
ElizaOS	npm i github:rezearcher/plugin-swap-gate	integrations/elizaos-plugin-swap-gate
LangChain.js	npm i github:rezearcher/langchain-swap-gate @langchain/core zod	integrations/langchain-swap-gate
Vercel AI SDK	npm i github:rezearcher/vercel-ai-swap-gate ai zod	integrations/vercel-ai-sdk-swap-gate

Install from git — this always pulls the current build (keyless free preview + inline x402, fails closed only if both are unreachable) and compiles on install via prepare. Each also exposes a tokenReport tool wrapping /chain/token-report for standalone token screening. Minimal copy-paste examples live under docs/examples/{swap-gate,langchain,elizaos}/.

Market-data buyer (for agents that buy a price and must not present stale data as real-time — the Decision402 pattern): examples/market-data-decision-buyer.mjs. Runs the full agentic loop — reads the live 402 quote, enforces a per-call USDC budget, proves the feed via the free preview, pays /crypto/prices ($0.001 on Base), then rejects any row older than MAX_AGE_SECONDS. Steps 1-3 run with zero npm installs: node examples/market-data-decision-buyer.mjs bitcoin,ethereum.

Python / LangChain / CrewAI

pip install "git+https://github.com/rezearcher/greyridge-x402-tools" — token_report() and swap_gate() helpers (free preview by default, paid x402 mode optional) plus LangChain tools. Guides: https://rezearcher.github.io/greyridge-x402-tools/

Try it on YOUR token, free

curl "https://x402-data-api.sigrunner.workers.dev/chain/token-report/preview?token=0xYourBaseToken" returns the same full-depth report as the paid route ($0.01). /gate/swap/preview?token=0x… gives 3 free real-token GO/HOLD/BLOCK checks/day/IP.

Agent skill (drop-in SKILL.md for OpenClaw/Hermes-style agents): https://github.com/rezearcher/greyridge-token-safety-skill

CI gate for MCP servers

uses: rezearcher/greyridge-x402-tools@v0.3.3 with url: runs the free MCP tool-poisoning preview in CI and fails on a block verdict. Every run also emits a copy-paste README injection-security badge (badge-markdown output / step summary; commit-badge: true auto-commits it between <!-- grsg-badge:start --> markers, degrade-open) — the OWASP-MCP (LLM01/LLM08) dimension generic repo-quality badges omit, re-checked on every CI run and linked to the server's live security report. Listed on the GitHub Marketplace. See actions/mcp-scan/README.md.

Python note: the default Python-urllib User-Agent is rejected with 403 at the Cloudflare edge. Use requests/httpx, or set any custom User-Agent header.