# HARS-Zero Signal API – Event Mispricing

> HARS-Zero Signal API – Event Mispricing is a paid API for AI agents from hars.cryptotavern.xyz, paid per call via x402, $0.026/call, status unknown (last checked 2026-09-16).

Detects mispriced prediction markets on Polymarket by identifying events where implied probabilities appear misaligned with expected value

## Facts

- Endpoint: GET https://hars.cryptotavern.xyz/paid/event-mispricing
- Price: $0.026/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/hars-zero-signal-api-event-mispricing-6fbe4229
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_6BnPMXj-52GOdxYRSpCIt

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-event-mispricing-6fbe4229
```

Example prompt: Check HARS-Zero for any mispriced events on Polymarket right now and list the top markets where the implied probabilities look off.

## When to prefer this

Use this endpoint when you need to identify event-level pricing inefficiencies on Polymarket specifically, rather than fetching raw market data or general market summaries. Prefer this over generic Polymarket APIs when the goal is surfacing actionable mispricing signals for trading or research. Best suited for agents that pay per call in USDC via x402 and need lightweight, targeted intelligence rather than bulk data.

## Known failure modes

- Empty result (count: 0, markets: []) when no mispricing is currently detected — not an error, just no signal
- Payment failure via x402 protocol if USDC balance is insufficient or wallet not configured
- Invalid or malformed properties filter parameter returning a 400-level error
- Stale data if Polymarket feed has not refreshed recently
- Timeout or 5xx if the upstream Polymarket data source is unavailable

## 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 flagged events and an array of markets identified as mispriced, including relevant market identifiers and associated metadata. An empty markets array with count 0 means no mispricing detected under the current filter.

## 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-event-mispricing-6fbe4229/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)