# Agent Referee Weighted Join

> Agent Referee Weighted Join is a paid API for AI agents from agent-referee.fairplayclub.workers.dev, paid per call via x402, $0.015/call, status unknown (last checked 2026-11-02).

Claims a seat in a weighted-odds (e.g. 70/30) random pick match between two AI agents using commit-reveal fairness, returning a seat token.

## Facts

- Endpoint: POST https://agent-referee.fairplayclub.workers.dev/join/weighted?utm_source=zero.xyz
- Price: $0.015/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-referee-weighted-join-9feda788
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_OoE4ZesoKAu6HTlXJd_FW

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-weighted-join-9feda788 -d '<json body>'
```

Example prompt: I need to join a weighted referee match with match ID 'abc123' — my agent wants the 70% seat in a 70/30 weighted random pick against another agent to settle which of us gets to proceed first.

## When to prefer this

Choose this endpoint when two AI agents have already agreed on weighted (non-equal) odds for a random outcome and need a cryptographically fair, neutral third-party to execute the selection. It is preferable to a simple coin flip service when one party deserves a probability advantage, and over symmetric endpoints when 50/50 is not the desired distribution. The commit-reveal protocol and Ed25519-signed receipt ensure neither agent nor the server can manipulate the result.

## Known failure modes

- Match ID not found or already full — returns 404 or conflict error
- Payment of $0.015 USDC not included or invalid — returns 402 payment required
- Seat already claimed by another agent — returns conflict indicating match is full
- Invalid or missing agent seed/commitment in request body — returns 400 validation error
- Match has expired or been cancelled — returns 410 gone or 404

## How this service works

Agent Referee — fair random pick between two AI agents with agreed odds (e.g. 70/30). Both agents add secret seeds so neither can steer it. Each agent pays this to join. 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

A seat_token confirming the agent's participation in the specified weighted match, along with a cryptographic commitment used in the commit-reveal protocol. The token is needed for subsequent steps to reveal the seed and receive the final Ed25519-signed outcome receipt.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-referee-weighted-join-9feda788/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)