# HALOWERK defiwerk Oracle Cross-Check

> HALOWERK defiwerk Oracle Cross-Check is a paid API for AI agents from defi.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-13).

Cross-checks crypto asset prices across Chainlink, Pyth, RedStone, CEX tickers, and Uniswap V3 spot/TWAP, returning each source's price, age, and a median with maximum deviation in basis points

## Facts

- Endpoint: POST https://defi.halowerk.com/oracle/crosscheck?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-defiwerk-oracle-cross-check-1e41e8b6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_s60yJeSiwchFTrWZWnvxS

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability halowerk-defiwerk-oracle-cross-check-1e41e8b6 -d '<json body>'
```

Example prompt: Cross-check the ETH price on Base right now using all available sources — Chainlink, Pyth, RedStone, CEX tickers, and the Uniswap V3 spot and 30-minute TWAP — and tell me the median, the worst-case deviation in basis points, and which sources are stale.

## When to prefer this

Choose this endpoint when you need to verify that multiple independent price sources agree before triggering a DeFi action, detect oracle manipulation or staleness, audit price feed health for a protocol, or when you explicitly need a 30-minute TWAP alongside spot prices. Prefer this over a single-oracle price feed whenever disagreement between sources is itself informative — e.g. before large trades, liquidation calls, or collateral valuation. It covers Base, Ethereum, Arbitrum, Optimism, and Polygon and a curated set of assets whose sources have been individually verified on-chain.

## Known failure modes

- Asset not supported on the requested chain returns a 400 or empty source list
- Chain not yet indexed returns an error or partial results
- Individual oracle sources may be absent if they lack a verified deployment for the asset/chain pair
- Stale oracle data is reported with a high age-in-seconds value rather than rejected
- Network congestion may delay on-chain reads, increasing response latency
- Uniswap V3 pool not found for the asset/USDC pair on a given chain returns missing DEX fields

## How this service works

Reads a Chainlink aggregator directly from the chain, pulls Pyth and RedStone, queries public exchange tickers and derives spot plus a 30-minute TWAP from the deepest Uniswap V3 pool of the asset against USDC on the requested chain. Every source carries its own age in seconds, its own price and a link to verify it. Nothing is smoothed into an average: the median is stated alongside the full list and the maximum deviation in basis points, because disagreement between sources is the finding, not a

## Output

Returns a per-source breakdown listing each oracle's name, current price, age in seconds, and a verification link, alongside a computed median price and the maximum deviation across all sources expressed in basis points. The Uniswap V3 component includes both a live spot price and a 30-minute TWAP from the deepest available pool against USDC on the requested chain. No blended average is produced — divergence between sources is surfaced explicitly as the primary signal.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "asset": {
   "enum": [
    "ETH",
    "BTC",
    "USDC",
    "USDT",
    "DAI",
    "LINK",
    "CBETH",
    "AERO"
   ],
   "type": "string",
   "description": "Asset symbol. Only assets whose sources were individually verified against the chain are available."
  },
  "chain": {
   "enum": [
    "base",
    "ethereum",
    "arbitrum",
    "optimism",
    "polygon"
   ],
   "type": "string",
   "description": "Chain the on-chain sources are read from. Off-chain sources are chain independent."
  },
  "oracles": {
   "type": "array",
   "items": {
    "enum": [
     "chainlink",
     "pyth",
     "redstone",
     "cex",
     "dex_spot",
     "dex_twap"
    ],
    "type": "string"
   },
   "description": "Optional filter for source types. Omitted means all available types."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-defiwerk-oracle-cross-check-1e41e8b6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from defi.halowerk.com](https://www.zero.xyz/host/defi.halowerk.com/llms.txt)