# Halowerk MMR Matchmaking Pair Selector

> Halowerk MMR Matchmaking Pair Selector is a paid API for AI agents from gaming.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-14).

Enumerates feasible player pairs from a pool, ranks them by rating gap then worst latency, and greedily selects disjoint matched pairs within configurable skill and latency constraints.

## Facts

- Endpoint: POST https://gaming.halowerk.com/v1/matchmaking-mmr
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-mmr-matchmaking-pair-selector-501d9c92
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_6IL3GmiL5WVc6JqaygzUo

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 halowerk-mmr-matchmaking-pair-selector-501d9c92 -d '<json body>'
```

Example prompt: I have 8 players waiting in the lobby — can you pair them up for matches using their MMR ratings and ping times, keeping rating gaps under 200 and latency under 80ms?

## When to prefer this

Use this endpoint when you have a known pool of players (2–500) with pre-measured latency and existing skill ratings and need a fast, deterministic, locally computed greedy pairing — not a global queue, live matchmaking service, anti-smurfing system, or team-balancing optimizer. Ideal for lobby-side or tournament-bracket pairing where you control the player set and want transparent, reproducible pair selection.

## Known failure modes

- Fewer than 2 players provided — no pairs can be formed
- All player combinations exceed max_rating_gap or max_latency_ms thresholds — returns empty pair list
- Player data missing required fields (player_id, rating, rating_uncertainty, latency_ms) — validation error
- More than 500 players submitted — exceeds maxItems constraint
- Latency or rating values out of declared range — schema validation failure

## How this service works

Enumerates feasible player pairs, ranks them by rating gap then worst latency, and greedily selects disjoint pairs. This is a transparent local pairing heuristic, not globally optimal team balancing, skill inference, anti-smurfing, or a live queue service.

## Output

Returns a list of greedily selected disjoint player pairs that satisfy the max_rating_gap and max_latency_ms constraints, ranked by rating gap and then worst latency among feasible pairs. Includes the paired player IDs and the metrics used for ranking each pair.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "players": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "player_id",
     "rating",
     "rating_uncertainty",
     "latency_ms"
    ],
    "properties": {
     "rating": {
      "type": "number",
      "maximum": 10000,
      "minimum": 0
     },
     "player_id": {
      "type": "string",
      "maxLength": 128,
      "minLength": 1
     },
     "latency_ms": {
      "type": "number",
      "maximum": 100000,
      "minimum": 0
     },
     "rating_uncertainty": {
      "type": "number",
      "maximum": 5000,
      "minimum": 0
     }
    },
    "additionalProperties": false
   },
   "maxItems": 500,
   "minItems": 2
  },
  "max_latency_ms": {
   "type": "number",
   "maximum": 100000,
   "minimum": 0
  },
  "max_rating_gap": {
   "type": "number",
   "maximum": 10000,
   "minimum": 0
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-mmr-matchmaking-pair-selector-501d9c92/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from gaming.halowerk.com](https://www.zero.xyz/host/gaming.halowerk.com/llms.txt)