# Polymarket Market Counterparty Screener (Size-the-Room)

> Polymarket Market Counterparty Screener (Size-the-Room) is a paid API for AI agents from graphadvocate.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-11).

Returns the top N holders of a Polymarket market ranked by skill_score, with per-holder ghost-fill settlement risk, for pre-trade counterparty assessment.

## Facts

- Endpoint: POST https://graphadvocate.com/polymarket/screen?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/graphadvocate-com-89d6cecd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_cx9dpj7mXLm47TU08w1bn

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 graphadvocate-com-89d6cecd -d '<json body>'
```

Example prompt: Before I trade on Polymarket condition 0xabc123, show me the top 10 holders ranked by skill score and flag which ones have ghost-fill settlement risk so I know what I'm walking into.

## When to prefer this

Use this endpoint when an AI trading or market-making agent needs to perform a pre-trade counterparty screen on a specific Polymarket market — specifically when both skill ranking AND ghost-fill settlement risk are needed together for the top N holders. Prefer this over the individual skill-score or ghost-fill endpoints when you need a holistic view of the competitive landscape for a single market in one call.

## Known failure modes

- Invalid or unknown condition_id returns an error or empty result
- n exceeds maximum (25) may return error or be capped
- Polymarket on-chain data lag may cause stale holder rankings
- Network or payment failure returns HTTP 402 or 5xx
- No holders found for a very new or illiquid market

## How this service works

Claude-powered routing agent for The Graph Protocol. Ask in plain English; paid calls run the query against 15,500+ indexed subgraphs and return the rows. Free chat hands you the subgraph and the GraphQL to run yourself. $0.01 USDC per call on Base via x402.

## Output

A ranked list of the top N holders (default 10, max 25) for the given Polymarket condition_id, each with their skill_score (0-100), wallet classification (EOA or smart account), and per-holder ghost-fill settlement risk level — enabling the agent to assess whether counterparty fills are likely to settle and how skilled those counterparties are.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "condition_id"
     ],
     "properties": {
      "n": {
       "type": "integer",
       "default": 10,
       "maximum": 25,
       "minimum": 1
      },
      "condition_id": {
       "type": "string",
       "description": "Polymarket condition_id (0x + 64 hex chars)"
      }
     }
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "holders": [
   {
    "rank": 1,
    "side": "Yes",
    "wallet": "0x38e5...",
    "skill_score": 71.4,
    "wallet_type": "smart_account_erc1967",
    "classification": "sharp",
    "ghost_fill_risk": "low",
    "position_value_usdc": 9005.64
   }
  ],
  "sharp_count": 3,
  "condition_id": "0x6331...",
  "retail_count": 4,
  "neutral_count": 2,
  "holders_screened": 10,
  "insufficient_data_count": 1,
  "ghost_fill_risk_breakdown": {
   "low": 6,
   "high": 1,
   "medium": 3
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/graphadvocate-com-89d6cecd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from graphadvocate.com](https://www.zero.xyz/host/graphadvocate.com/llms.txt)