/polymarket

name: polymarket
description: "Query Polymarket: markets, prices, orderbooks, history."
version: 1.0.0
author: Hermes Agent + Teknium
tags: [polymarket, prediction-markets, market-data, trading]
origin: original
source_repo: kevinnft/ai-agent-skills
source_url: https://github.com/kevinnft/ai-agent-skills
source_license: MIT
language: en

Polymarket — Prediction Market Data

Query prediction market data from Polymarket using their public REST APIs. All endpoints are read-only and require zero authentication.

See `references/api-endpoints.md` for the full endpoint reference with curl examples.

When to Use

• User asks about prediction markets, betting odds, or event probabilities
• User wants to know "what are the odds of X happening?"
• User asks about Polymarket specifically
• User wants market prices, orderbook data, or price history
• User asks to monitor or track prediction market movements

Key Concepts

• **Events** contain one or more **Markets** (1:many relationship)
• **Markets** are binary outcomes with Yes/No prices between 0.00 and 1.00
• Prices ARE probabilities: price 0.65 means the market thinks 65% likely
• `outcomePrices` field: JSON-encoded array like `["0.80", "0.20"]`
• `clobTokenIds` field: JSON-encoded array of two token IDs [Yes, No] for price/book queries
• `conditionId` field: hex string used for price history queries
• Volume is in USDC (US dollars)

Three Public APIs

1. **Gamma API** at `gamma-api.polymarket.com` — Discovery, search, browsing 2. **CLOB API** at `clob.polymarket.com` — Real-time prices, orderbooks, history 3. **Data API** at `data-api.polymarket.com` — Trades, open interest

Typical Workflow

When a user asks about prediction market odds:

1. **Search** using the Gamma API public-search endpoint with their query 2. **Parse** the response — extract events and their nested markets 3. **Present** market question, current prices as percentages, and volume 4. **Deep dive** if asked — use clobTokenIds for orderbook, conditionId for history

Presenting Results

Format prices as percentages for readability:

• outcomePrices `["0.652", "0.348"]` becomes "Yes: 65.2%, No: 34.8%"
• Always show the market question and probability
• Include volume when available

Example: `"Will X happen?" — 65.2% Yes ($1.2M volume)`

Parsing Double-Encoded Fields

The Gamma API returns `outcomePrices`, `outcomes`, and `clobTokenIds` as JSON strings inside JSON responses (double-encoded). When processing with Python, parse them with `json.loads(market['outcomePrices'])` to get the actual array.

Rate Limits

Generous — unlikely to hit for normal usage:

• Gamma: 4,000 requests per 10 seconds (general)
• CLOB: 9,000 requests per 10 seconds (general)
• Data: 1,000 requests per 10 seconds (general)

Limitations

• This skill is read-only — it does not support placing trades
• Trading requires wallet-based crypto authentication (EIP-712 signatures)
• Some new markets may have empty price history
• Geographic restrictions apply to trading but read-only data is globally accessible