mcp-gauge-x402

v1.0.5

Published

a month ago

Verify official facts before your AI agent acts — multi-source cross-validation with tamper-proof receipts on Bitcoin. 180+ signals (USGS/NOAA/SEC/EPA + more). x402 pay-per-call in USDC, no API key.

mcp-gauge — Verifiable facts for AI agents, pay-per-call via x402

Check official facts before your AI agent acts. 180+ signals from USGS, NOAA, SEC EDGAR, EPA, and more — each response includes multi-source cross-validation and a tamper-proof receipt anchored to Bitcoin via OpenTimestamps. No API key, no signup. Pay per call in USDC on Base via x402.

Quick start

Claude Desktop

Add to your config (~/Library/Application Support/Claude/claude_desktop_config.json on macOS, %APPDATA%\Claude\claude_desktop_config.json on Windows):

{
  "mcpServers": {
    "gauge": {
      "command": "npx",
      "args": ["-y", "mcp-gauge-x402"],
      "env": {
        "EVM_PRIVATE_KEY": "0x..."   // optional — omit for free tools only
      }
    }
  }
}

Cursor

Add to .cursor/mcp.json in your project root (or global config):

{
  "mcpServers": {
    "gauge": {
      "command": "npx",
      "args": ["-y", "mcp-gauge-x402"],
      "env": {
        "EVM_PRIVATE_KEY": "0x..."   // optional — omit for free tools only
      }
    }
  }
}

Claude Code

claude mcp add gauge -- npx -y mcp-gauge-x402
# For paid tools, add the env:
claude mcp add gauge --env EVM_PRIVATE_KEY=0x... -- npx -y mcp-gauge-x402

Other MCP hosts

Any MCP client that supports stdio transport works. Command: npx -y mcp-gauge-x402, set EVM_PRIVATE_KEY in env for paid tools.

Alternative: install from GitHub (no npm account needed):
npx -y github:CHANGCHINFU/mcp-gauge

From source

git clone https://github.com/CHANGCHINFU/mcp-gauge && cd mcp-gauge
npm install && npm run build
node dist/index.js

Payment setup

| | Without EVM_PRIVATE_KEY | With EVM_PRIVATE_KEY | |---|---|---| | Free tools | Yes | Yes | | Paid tools | No (tools visible but calls fail) | Yes (auto-pays via x402) |

How it works: When your agent calls a paid tool, the GAUGE server returns an x402 payment challenge. The MCP client automatically pays in USDC on Base (EIP-3009 gasless — no ETH needed) and retries the request. The receipt is included in every response.

Wallet safety:

Use a dedicated burner wallet with a small USDC balance — never your main wallet
The private key never leaves your machine (processed locally by x402-fetch)
Fund with just enough USDC for your expected usage
Network: Base mainnet (Coinbase L2)

Tools

Free (no wallet needed)

| Tool | What it does | |---|---| | gauge_catalog | Browse 180+ available signals | | gauge_preview | Coverage, pricing menu, bundle contents | | gauge_sample | Full sample record with Bitcoin receipt | | gauge_river_free | US river gauge reading (USGS) with receipt | | gauge_anchor | Look up Bitcoin proof for any record_hash |

Paid — single-source verification

| Tool | What it does | |---|---| | verify_signal | Check one official fact from 180+ signals. Bitcoin-anchored receipt. | | gauge_flood_risk | Hydrology / air / precipitation alias of verify_signal | | gauge_resolution_as_of | Prediction-market settlement — official fact + evidence + receipt |

Paid — 3-source cross-validation bundles

| Tool | What it cross-checks | |---|---| | gauge_region | Air quality + precipitation + river level | | gauge_crop_drought | Drought severity + heat/GDD + satellite crop health | | gauge_grid_stress | Demand pressure + renewable output + energy inflation | | gauge_route_disruption | Sea state + wave cause + live AIS vessel traffic | | gauge_filing_check | SEC 8-K events + late filing + insider buy/sell | | gauge_stablecoin_lifecycle | Peg drift + redemption acceleration + protocol exposure | | gauge_rwa_lifecycle | Issuer lifecycle + redemption pressure + downstream exposure | | gauge_lrt_lifecycle | Discount-to-NAV + withdrawal queue + collateral cascade | | gauge_defi_lending | Utilization + bad-debt pressure + contagion | | gauge_depin_network | Network liveness + reward churn + downstream exposure |

Prices are set by the live x402 challenge (use gauge_preview to check current pricing). If you drive the API with your own x402 client, set maxValue to at least $0.25 — the default $0.10 makes your client reject bundle tools locally.

Environment variables

| Key | Required | Description | |---|---|---| | EVM_PRIVATE_KEY | For paid tools | Base-mainnet wallet private key (0x...). Needs USDC, no ETH. | | GAUGE_BASE_URL | No | API endpoint. Default: https://api.truthbear.co | | GAUGE_MAX_USDC | No | Atomic per-call cap in USDC (6 decimals). Default: 350000 |

Zero-trust verification

Every paid record carries a record_hash (canonical SHA-256). Daily Merkle roots are stamped to Bitcoin via OpenTimestamps. The stamp proves the record set existed no later than stamped_at. Re-check anytime:

gauge_anchor tool (free)
POST /verify or /proof/:record_hash at the GAUGE API
Download attestation bytes and verify with the official ots CLI

FAQ

Do I need ETH for gas? No. x402 uses EIP-3009 (gasless USDC transfer). You only need USDC on Base.

What if I don't set a private key? You can still use all 5 free tools. Paid tools will be listed but return an error when called.

Is my private key sent to the server? No. The key stays on your machine. x402-fetch signs the payment locally and sends only the signed authorization to the GAUGE server.

What happens if the data isn't available? The tool honest-fails with no charge. You only pay when you get a result.

Can I verify the receipt without your server? Yes. Download the OpenTimestamps attestation via gauge_anchor and verify with the standard ots CLI tool against any Bitcoin node.