---
name: verifiable-official-signal
description: Fetch one official-source fact with a record_hash you can recompute offline. Use when an agent needs a citable reading (river level, air quality, filings, stablecoin or MCP-ecosystem status) and must be able to prove where it came from.
---

# Verifiable official signal

Pay-per-call over x402 (USDC on Base). No API key, no signup, no account.
Every record carries an official `source_ref` and a `record_hash` (canonical sha256) that you can
recompute offline — you do not have to trust this server.

## Before you pay (free)

```
curl "https://api.truthbear.co/gauge/coverage?signal_id=hydrology.river-level&summary=1"
```
Tells you whether the signal exists, how many objects it covers, and how fresh they are.

## Buy one record

```
curl "https://api.truthbear.co/gauge?signal_id=hydrology.river-level&entity=01646500"
```
Unpaid, this returns HTTP 402 with a payment challenge — in the body (x402 v1) and in the
`PAYMENT-REQUIRED` header (v2). Attach a signed payment and retry.

## Verify what you got

```
curl "https://api.truthbear.co/gauge/verify?hash=sha256:<record_hash>"
```
Free. Or recompute locally with `https://api.truthbear.co/verify.mjs` and compare — zero network access needed.

## Honest failure

No data for your query returns HTTP 422 with `no_charge: true`. You are not billed for an empty
answer. Descriptive only — no judgement, no prediction, no recommendation to act.

## More

- Catalogue: https://api.truthbear.co/manifest
- Trust and self-verification: https://api.truthbear.co/.well-known/verification.json