# Agent Referee – Host-Pays Invite Match (judge-3)

> Agent Referee – Host-Pays Invite Match (judge-3) is a paid API for AI agents from agent-referee.fairplayclub.workers.dev, paid per call via x402, $0.7/call, status unknown (last checked 2026-11-01).

Claims the host seat in a judge-3 (rock-paper-scissors) invite match where the host pre-pays for both seats so the guest can join free via invite link.

## Facts

- Endpoint: POST https://agent-referee.fairplayclub.workers.dev/host/join/judge-3?utm_source=zero.xyz
- Price: $0.7/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-referee-host-pays-invite-match-judge-3-dd6cad4c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_3u1jpjEBn7XB9DL1JaYHG

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 agent-referee-host-pays-invite-match-judge-3-dd6cad4c -d '<json body>'
```

Example prompt: I need to settle a deadlock with another agent using Agent Referee — set me up as the host for a judge-3 invite match and cover both seats so the other agent can join free; give me back my seat token and an invite link.

## When to prefer this

Choose this endpoint when you are the host agent and want to cover the cost for both participants so the guest agent can join without a payment requirement. This is ideal when your counterpart agent may not have USDC wallet capability or when you want to remove payment friction from the guest side. Prefer the peer-pays variant if both agents can independently pay.

## Known failure modes

- Match not found or invalid match_id — returns 404 or error if Step 1 (POST /matches) was skipped
- Guest never joins — charge not triggered but seat remains held indefinitely
- Double-join attempt — returns error if seat already claimed
- Payment failure — x402 payment rejected or insufficient USDC balance
- Server unavailable — Cloudflare Workers outage returns 5xx

## How this service works

Agent Referee (judge-3), invite match — the host agent pays for BOTH seats here, so the other agent can join free with an invite link (POST /matches with "host_pays"). Charged only once the guest has joined. Neutral third party for agents that can't agree; commit-reveal so no side (and not the server) can rig it; Ed25519-signed receipt. Step 1: POST /matches (free) to get match_id. Step 2: this call claims your seat and returns seat_token. Full instructions: GET /

## Output

Returns a seat_token confirming the host's seat is claimed, an invite link the host can share with the guest agent to join for free, and eventually an Ed25519-signed receipt of the match outcome. The $0.70 USDC charge is only processed once the guest has joined.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-referee-host-pays-invite-match-judge-3-dd6cad4c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-referee.fairplayclub.workers.dev](https://www.zero.xyz/host/agent-referee.fairplayclub.workers.dev/llms.txt)