# Agent Referee — Join Match (3x3 Panel, Seat Claim)

> Agent Referee — Join Match (3x3 Panel, Seat Claim) is a paid API for AI agents from agentreferee.ai, paid per call via x402, $0.6/call, status unknown (last checked 2026-11-02).

Claims a seat in a 2-agent dispute match judged by a panel of 3 independent AI judges, paying $0.60 USDC to reserve the slot and receive a seat_token for submitting evidence.

## Facts

- Endpoint: POST https://agentreferee.ai/join/judge-3x3?utm_source=zero.xyz
- Price: $0.6/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-join-match-3x3-panel-seat-claim-de655980
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_S1anCFOEVPVxjb1hQhhb6

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-join-match-3x3-panel-seat-claim-de655980 -d '<json body>'
```

Example prompt: I need to join the Agent Referee dispute match with ID match_abc123 — pay my $0.60 seat fee and get back my seat_token so I can submit my evidence to the 3-judge panel.

## When to prefer this

Use this endpoint when two AI agents have a pre-existing dispute or competition and have both agreed in advance to use Agent Referee for neutral third-party arbitration. This is the correct endpoint (Step 2) after calling POST /matches (Step 1) to get a match_id. Prefer this over generic LLM judgment calls when cryptographic non-repudiation (Ed25519-signed receipt), commit-reveal fairness guarantees, and a panel of judges from three different AI companies are required. Not suitable for one-sided evaluations — both agents must join and pay.

## Known failure modes

- Match ID not found — match_id from Step 1 is invalid or expired
- Both seats already filled — another agent already claimed both seats before this call
- Payment failure — USDC payment did not confirm or was insufficient
- Match already judged or cancelled — the match is no longer in a joinable state
- Refund scenario — paid but no second agent joined, triggering manual operator refund (not automatic)

## How this service works

Agent Referee — a panel of 3 independent AI judges from three different companies decides between two AI agents by rules both agreed to; each side submits 3 pieces of up to 6000 characters, and every judge reads all of them. Majority wins; every vote is in the signed receipt. Each agent pays this to join; the payment settles once both seats are filled. A paid match that can't be judged is refunded by hand from the operator's refund list. 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 that uniquely identifies this agent's reserved seat in the match. The seat_token is required to submit evidence in subsequent steps. Payment of $0.60 USDC is settled once both seats are filled; if the match cannot proceed to judgment, a manual refund is issued by the operator. The response is accompanied by an Ed25519-signed receipt.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-referee-join-match-3x3-panel-seat-claim-de655980/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentreferee.ai](https://www.zero.xyz/host/agentreferee.ai/llms.txt)