Simmer MCP Server

Simmer is the leading prediction market harness for AI agents. Autonomous agents place trades on venues like Polymarket, Kalshi and Hyperliquid through a unified API - with self-custody wallets, safety rails, and smart context. It runs locally over stdio via the published package.

People connecting this server to Claude, Cursor, VS Code, or another MCP client. The project is written in Python.

VERIFIED ACTIVE

LAST COMMIT 2026-08-24 · ★ 48 · #79 OF 848 MAINTAINED OTHER · VERIFIED 2026-08-25

MIT · Python servers · how we verify → /methodology

01 · Install Simmer

before you install - you'll need

Set SIMMER_API_KEY, TRADING_VENUE, WALLET_PRIVATE_KEY before connecting.

Claude Code

claude mcp add spartanlabsxyz-simmer-sdk -- npx -y simmer-mcp

Claude Desktop / Cursor / VS Code - add to config

{
  "mcpServers": {
    "spartanlabsxyz-simmer-sdk": {
      "command": "npx",
      "args": [
        "-y",
        "simmer-mcp"
      ]
    }
  }
}

Same JSON for Cursor. For VS Code, rename the top-level key from `mcpServers` to `servers`.

Using another client? Same JSON, different key

Claude Desktop · mcpServers

Cursor · mcpServers

VS Code · servers

Windsurf · mcpServers

Zed · context_servers

Cline · mcpServers

Roo Code · mcpServers

Continue · mcpServers

LibreChat · mcpServers

Gemini CLI · mcpServers

Codex CLI · mcp_servers

Full setup guides: every client.

02 · Evidence

Security posture

What to check before giving this server access to your agent - from the registry, GitHub, and our own probes. We don't score safety; we show what's verifiable.

runs as local process (stdio) - runs on your machine with your user's permissions

license MIT - declared in the repository

npm package simmer-mcp - unscoped; check the name against the project README before installing

registry registry publisher io.github.adlai88 is not the repo owner (spartanlabsxyz) - the registry entry was published by someone else

03 · Who maintains Simmer

Simmer is maintained by spartanlabsxyz. It's the only MCP server we track from this author; the repo dates to Jan 2026.

04 · Facts

repository: github.com/spartanlabsxyz/simmer-sdk
website: https://simmer.markets/
category: other - ranked #79 of 848 actively-maintained other servers as of 2026-08-25.
registry: io.github.adlai88/simmer-mcp (active, first published 2026-05-24)
packages: npm:simmer-mcp

05 · Simmer FAQ

What is Simmer?

Is Simmer still maintained?

Yes - as of 2026-08-25, its last commit was 2026-08-24. We re-verify nightly.

How do I install Simmer?

Run `npx -y simmer-mcp`. The README documents 3 environment variables (SIMMER_API_KEY, TRADING_VENUE, WALLET_PRIVATE_KEY) to set first. Set SIMMER_API_KEY, TRADING_VENUE, WALLET_PRIVATE_KEY before connecting. You can also paste the ready-made client config above.

Does Simmer run locally?

Yes - it's a stdio server: it runs on your machine (via npx) with your user's permissions. Your data stays local unless the server itself calls external APIs.

06 · Alternatives to Simmer

Alternatives to Simmer

Maintained other servers if Simmer isn't the fit.

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