Polymarket Guard
Wire Claude Code or Cursor to Polymarket so your agent can quote markets and place USDC buy/sell trades with optional LemonCake pay-per-call billing.
Overview
Polymarket Guard is an MCP server for the Build phase that lets agents query and trade Polymarket positions in USDC with optional LemonCake pay-per-call billing.
What is this MCP server?
- stdio npm package polymarket-guard-mcp (v0.1.0) for MCP-compatible agents
- Buy and sell prediction-market positions settled in USDC on Polygon
- Read-only mode when POLYMARKET_PRIVATE_KEY is unset
- LemonCake Buyer JWT (LEMON_CAKE_BUYER_JWT) for metered pay-per-call usage
- Secrets documented in server.schema environmentVariables for wallet and billing
- Server version 0.1.0
- Transport: stdio; npm identifier polymarket-guard-mcp
- 2 secret env vars: POLYMARKET_PRIVATE_KEY, LEMON_CAKE_BUYER_JWT
What problem does it solve?
You want your agent to act on Polymarket odds and positions without building a custom CLOB client and payment meter from scratch.
Who is it for?
Solo builders shipping agent experiments around prediction markets who already manage Polygon keys and want MCP-native tooling.
Skip if: Anyone who needs regulated brokerage workflows, zero crypto exposure, or a UI-first trading dashboard without agent integration.
What do I get? / Deliverables
After you register the stdio server and keys, your agent can invoke MCP tools for market access and controlled USDC trades under your configured secrets.
- Registered stdio MCP server polymarket-guard-mcp in your agent config
- Agent-callable Polymarket market and trade tools under your secret policy
Recommended MCP Servers
Journey fit
Solo builders add this while composing agent tooling and external APIs, before anything is production-operated as a trading bot. It is an MCP stdio bridge to Polymarket and billing, not a standalone app feature or launch distribution play.
How it compares
MCP trading integration on Polymarket, not a general research skill or backtesting framework.
Common Questions / FAQ
Who is polymarket-guard for?
It is for indie developers wiring Claude Code, Cursor, or other MCP clients to Polymarket with USDC positions and optional LemonCake metering.
When should I use polymarket-guard?
Use it during Build integrations when you need agent-callable buy/sell or read-only market access, after you understand wallet and billing env vars.
How do I add polymarket-guard to my agent?
Add the polymarket-guard-mcp npm stdio server to your MCP config, set LEMON_CAKE_BUYER_JWT if billing applies, and set POLYMARKET_PRIVATE_KEY only when you intend live trading.