mcp-gauge — MCP server for GAUGE (verifiable signals, pay-per-call in USDC via x402)
Give any MCP host (Claude Desktop, Cursor, MCP-compatible agents) access to GAUGE's verifiable, screening-level signals across many domains (weather, drought, agriculture, power grid, shipping, regulatory filings, and more) — and let the agent pay per call in USDC on Base via x402 (EIP-3009 gasless, no API key, no signup).
Pure description — official-source facts (USGS / NOAA / EPA / CAMS / ERA5 / FRED / Open-Meteo Marine / SEC EDGAR) + back-testable statistics + record_hash (canonical sha256, recomputable offline). The agent decides. Payment settles directly to the provider wallet.
Backed by the GAUGE service at https://aeml-x402.zeabur.app.
Part of Truth Bear 🐻 — GAUGE is the data engine behind Truth Bear, the natural-language front desk for AI agents and SMBs. Ask in plain language, get the official fact + its source + a verifiable record_hash — no prediction, no advice, the rest is your call. An analyst, not a commander. Front desk: https://gauge-frontdesk.zeabur.app · discovery: /.well-known/x402, /llms.txt.
Why MCP + x402
- Discovery is free and open (MCP): any MCP host lists these tools with zero setup.
- Payment is crypto (x402): the agent pays USDC only when it calls a paid tool.
- Free tools (
gauge_catalog, gauge_preview, gauge_sample, gauge_river_free) need no wallet — try before you buy.
| Tool | Price | What |
|---|
gauge_catalog | free | All signals + queryable entities |
gauge_preview | free | Coverage, pricing menu, bundle lists |
gauge_sample | free | A full sample record (what paid looks like) |
gauge_river_free | free | Raw US river reading (USGS site id) |
gauge_flood_risk | $0.05 | Flood-risk/anomaly record vs official thresholds + seasonal anomaly + hash |
gauge_region | $0.10 | City bundle: air + precipitation + river + cross-check |
gauge_crop_drought | $0.10 | Agriculture triangle: drought (USDM) + heat/GDD + crop VHI |
gauge_grid_stress | $0.10 | Power grid triangle: demand + renewables + energy inflation |
gauge_route_disruption | $0.10 | Shipping triangle: route disruption + sea state + AIS throughput |
gauge_filing_check | $0.10 | Regulatory-filing triangle: 8-K + late filing + Form 4 insider |
130+ signals (and growing) across hydrology, air quality, precipitation, agriculture, power grid, shipping and regulatory filing — with global coverage (US plus Argentina, Brazil, China, India, Ukraine, EU and more). Check the live set anytime via the free gauge_catalog tool.
Two ways to connect (they are different servers)
| This package (stdio) | Hosted remote (Smithery) |
|---|
| How | npx -y github:CHANGCHINFU/mcp-gauge | smithery.ai/servers/truthbear/mcp-gauge |
| Tools | the gauge_* tools (main ones in the table below) | 3 tools: verify_citation, find_signal, get_official_record |
| Paid calls | this server pays for you, from EVM_PRIVATE_KEY | never takes payment — it hands you the real 402 challenge and you pay from your own wallet |
| Needs a wallet key | yes, for paid tools | no |
Pick the remote one if you don't want to put a private key in your MCP host config.
Requires Node 18+. The MCP host runs the server over stdio. Install straight from GitHub — no npm account, no signup (the built dist/ is committed):
npx -y github:CHANGCHINFU/mcp-gauge
Claude Desktop
Add to claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\):
{
"mcpServers": {
"gauge": {
"command": "npx",
"args": ["-y", "github:CHANGCHINFU/mcp-gauge"],
"env": {
"EVM_PRIVATE_KEY": "0xYOUR_BASE_WALLET_KEY_WITH_A_LITTLE_USDC"
}
}
}
}
Omit EVM_PRIVATE_KEY to use free tools only (catalog / preview / sample / river).
Cursor / other MCP hosts / Claude Code
- Claude Code:
claude mcp add gauge -- npx -y github:CHANGCHINFU/mcp-gauge (add --env EVM_PRIVATE_KEY=0x… for paid tools).
- Cursor / others: command
npx -y github:CHANGCHINFU/mcp-gauge, transport stdio, optional EVM_PRIVATE_KEY env.
From source
git clone https://github.com/CHANGCHINFU/mcp-gauge && cd mcp-gauge
npm install && npm run build
node dist/index.js
Once published to npm the package name is mcp-gauge-x402 (npx -y mcp-gauge-x402); until then use the GitHub form above.
Config (env)
| Key | Required | Description |
|---|
EVM_PRIVATE_KEY | for paid tools | 0x Base-mainnet wallet key; needs a little USDC (EIP-3009 gasless, no ETH). |
GAUGE_BASE_URL | no | Default https://aeml-x402.zeabur.app. |
GAUGE_MAX_USDC | no | Atomic per-call cap. Default 120000 ($0.12). |
Handle the private key like any hot-wallet secret; fund it with a small USDC balance only.
Verify (zero-trust)
Every paid record carries a record_hash — the canonical sha256 of the record's core fields, which you can
recompute yourself offline. Re-check a record via POST /verify, or look a hash up with GET /proof/:record_hash
or the free GET /gauge/verify?format=json&hash=…, at the GAUGE service.
Bitcoin / OpenTimestamps anchoring: RETIRED. It was ruled out of implementation on 2026-07-23 and was never
actually stamped. Earlier versions of this README advertised it — that was wrong, and this corrects it.
What you actually get: integrity from record_hash, and timeliness from the official source_ref
plus observed_at. The ots_status field is a legacy compatibility field and stays pending forever.
The live service says the same thing in GET /proof/:record_hash → proof.bitcoin_anchoring.
Distribution (maintainers)
- GitHub install (primary, no npm account): users run
npx -y github:CHANGCHINFU/mcp-gauge.
- awesome-mcp-servers: submit a PR to a curated MCP server list for discoverability (no npm needed).
- MCP Registry (optional, needs npm): publish
mcp-gauge-x402 to npm, then server.json is ready for the MCP publisher:
npm publish
mcp-publisher login github
mcp-publisher publish
MIT · AEML-DS Vanished-Data Exchange