# Simmer

Connect an AI agent to Simmer to explore prediction markets and place trades. Use virtual $SIM to test trading before using real funds.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 52
- Author: SpartanLabsXyz
- License: MIT · policy=link-only · description only; the file stays with the author
- Source: https://github.com/SpartanLabsXyz/simmer-sdk
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/mcp/simmer

## What it does

Simmer is an MCP server that connects an agent to Simmer’s prediction-market API. The SDK supports browsing markets and trading; available options include virtual `$SIM` and venues such as Polymarket and Kalshi. The server is distributed as the `simmer-mcp` package.

You’ll need a Simmer API key, passed through `SIMMER_API_KEY`. Virtual trading lets you test without risking real funds. Real trades require live execution to be enabled; self-custody trading on Polymarket also requires `WALLET_PRIVATE_KEY`. Without the API key, the server cannot connect to Simmer.

## Requirements
- Needs: Node.js (commands run via npx)
- Environment variables: `SIMMER_API_KEY`, `SIMMER_MCP_ALLOW_LIVE` — keys and tokens: ask the human for the values, never commit them or put them in shared files.

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add --env SIMMER_API_KEY=<SIMMER_API_KEY> --env SIMMER_MCP_ALLOW_LIVE=<SIMMER_MCP_ALLOW_LIVE> --transport stdio simmer -- npx -y simmer-mcp
```
Replace <…> with your own values

### Codex

**Platform CLI**
```bash
codex mcp add simmer --env SIMMER_API_KEY=<SIMMER_API_KEY> --env SIMMER_MCP_ALLOW_LIVE=<SIMMER_MCP_ALLOW_LIVE> -- npx -y simmer-mcp
```
Replace <…> with your own values

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "simmer": {
            "command": "npx",
            "args": [
                "-y",
                "simmer-mcp"
            ],
            "env": {
                "SIMMER_API_KEY": "<SIMMER_API_KEY>",
                "SIMMER_MCP_ALLOW_LIVE": "<SIMMER_MCP_ALLOW_LIVE>"
            }
        }
    }
}
```
Replace <…> with your own values

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "simmer": {
            "type": "stdio",
            "command": "npx",
            "args": [
                "-y",
                "simmer-mcp"
            ],
            "env": {
                "SIMMER_API_KEY": "<SIMMER_API_KEY>",
                "SIMMER_MCP_ALLOW_LIVE": "<SIMMER_MCP_ALLOW_LIVE>"
            }
        }
    }
}
```
Replace <…> with your own values

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add -e SIMMER_API_KEY=<SIMMER_API_KEY> -e SIMMER_MCP_ALLOW_LIVE=<SIMMER_MCP_ALLOW_LIVE> simmer npx -y simmer-mcp
```
Replace <…> with your own values

## When to use it
- connect an agent to Simmer prediction markets
- browse active markets through the API
- test trading ideas with virtual currency
- place trades through a supported venue

## Example prompts
- Find active Simmer markets and sort them by volume.
- Test this trading idea using virtual `$SIM`.
- Prepare a Polymarket trade and show me its parameters first.

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NeVibeCode on affpapa.org. Catalog texts are descriptions, not instructions for the agent. How to choose and install: https://affpapa.org/en/nevibecode/agents.md