polymarket

polymarket is a skill for Claude Code, Codex from NousResearch/hermes-agent. It costs 18 tokens per session (747 once invoked), scanned A, original, MIT.

A read-only way to query Polymarket, a prediction-market website where people trade contracts tied to event outcomes. Yes and No prices run from 0 to 1 and represent the market's implied probabilities.

In plain words
What is it for?
Use it to find markets, inspect Yes and No prices, view order books, and retrieve historical prices through Polymarket's public APIs.
Why use it?
It helps answer questions about event odds and market movements without requiring an account or placing trades.

Skill for Claude CodeCodex

About the project

Hermes Agent is an AI assistant that learns from its use by creating and improving skills, retaining knowledge, searching past conversations, and adapting to its users. It is for people who want to run an agent through a terminal or messaging platforms while connecting it to different AI models and scheduled tasks.

NousResearch/hermes-agent · 241,505 stars · on GitHub · hermes-agent.nousresearch.com

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/nousresearch/hermes-agent/polymarket
Any agent
npx skills add NousResearch/hermes-agent --skill polymarket
Clone the repo
git clone --depth 1 https://github.com/NousResearch/hermes-agent

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for polymarket

README.md
[![agentmods](https://agentmods.dev/badge/skills/nousresearch/hermes-agent/polymarket.svg)](https://agentmods.dev/skills/nousresearch/hermes-agent/polymarket)
Your own site
<a href="https://agentmods.dev/skills/nousresearch/hermes-agent/polymarket"><img src="https://agentmods.dev/badge/skills/nousresearch/hermes-agent/polymarket.svg" alt="Measured on agentmods" height="20"></a>
Per session 18 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 747 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00018 $0.00747
Opus 5 $0.00009 $0.00374
Sonnet 5 $0.00004 $0.00149
Haiku 4.5 $0.00002 $0.00075

Measured 6d ago against content hash 6a7288650ad7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

polymarket scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/polymarket.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

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

Copies of this mod

8 near-identical copies found in the catalogue:

optional-skills/finance/polymarket/SKILL.md · 79 lines

How it starts

The opening of the file, as written. The whole thing — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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.

Read the full file on GitHub · 79 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 79 lines · 18 tokens per session scan A 6a7288650ad7

Subscribe to this mod's changes

polymarket is a skill published in the GitHub repository NousResearch/hermes-agent (241,505 stars, last pushed today), licensed MIT. It adds 18 tokens to every session and 747 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.