# HARS-Zero Signal API – Historical Screener

> HARS-Zero Signal API – Historical Screener is a paid API for AI agents from hars.cryptotavern.xyz, paid per call via x402, $0.04/call, status unknown (last checked 2026-10-18).

Screens historical Polymarket prediction-market data to surface intelligence signals for AI agents, billed per call in USDC via x402.

## Facts

- Endpoint: GET https://hars.cryptotavern.xyz/paid/historical-screener?utm_source=zero.xyz
- Price: $0.04/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/hars-zero-signal-api-historical-screener-d36929ae
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_adoaN6MyQ08EqabO4mV2Y

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 hars-zero-signal-api-historical-screener-d36929ae
```

Example prompt: Pull me historical Polymarket markets related to US elections from HARS-Zero — I want to see which markets closed and what the outcomes were.

## When to prefer this

Choose this endpoint when you need to screen or filter historical Polymarket prediction-market data programmatically within an AI agent workflow, especially when paying per-call in USDC via x402 suits your architecture. Prefer it over direct Polymarket API access when you want pre-packaged intelligence signals rather than raw market data, or when operating on Base or Solana chains.

## Known failure modes

- Empty markets array and count=0 when no markets match the filter criteria
- 402 Payment Required if USDC payment via x402 is not included or insufficient
- Invalid or malformed properties filter may return an error or empty result
- Rate limiting or service unavailability returning 5xx errors
- Ambiguous filter properties leading to unexpectedly broad or narrow result sets

## How this service works

Polymarket prediction-market intelligence for AI agents. Pay-per-call in USDC via x402 protocol. Multi-chain: Base + Solana.

## Output

Returns a JSON object with a count of matched markets and an array of historical market records from Polymarket matching the supplied filter criteria. Markets array may be empty if no records match.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "example": {
  "count": 0,
  "markets": []
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/hars-zero-signal-api-historical-screener-d36929ae/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from hars.cryptotavern.xyz](https://www.zero.xyz/host/hars.cryptotavern.xyz/llms.txt)