mcp-server-kalshi 0.2.0

An MCP server implementation for Kalshi prediction market endpoints

MCP Server Kalshi

An MCP server that gives Claude Code and other agent harnesses a first-class interface to Kalshi, the regulated prediction-market exchange. It is built for deep, end-to-end trading: browse markets, research them, read the exact settlement rules (including pulling the contract-terms PDFs), and execute trades — all through MCP tools.

Highlights

• Discovery — list_markets, get_market, list_events, get_event, list_series, get_series. (Kalshi has no free-text search; list_markets filters are the search.)
• Research — get_market_orderbook, get_market_candlesticks, get_market_trades.
• Deep rules — get_market_rules consolidates a market's rules_primary/rules_secondary, early-close conditions, settlement sources, and series prohibitions; fetch_rules_pdf downloads and extracts the text of the actual legal contract PDF so the agent can read it.
• Exchange — get_exchange_status, get_exchange_schedule (is the market open, and its hours).
• Portfolio — get_balance, get_positions, get_fills, get_settlements.
• Trading — create_order, cancel_order, amend_order, decrease_order, plus list_orders / get_order.

Safety by default

• The server targets Kalshi's demo (sandbox) environment unless you explicitly set KALSHI_ENV=prod.
• Order-placing tools (create_order, amend_order) require confirm=true. Without it they return a preview — a human-readable summary and the exact payload — and place nothing.
• Credentials are optional: all market/rules tools work unauthenticated. Only portfolio and order tools need an API key + RSA private key.

Intuitive order model

Kalshi's V2 order API quotes everything from the YES leg (bid/ask in fixed-point dollars). This server exposes the natural model instead — action (buy/sell) + side (yes/no) + a whole cents limit price — and translates it (including the buy-NO ⇄ sell-YES price inversion).

Configuration

Variable	Default	Purpose
KALSHI_ENV	demo	demo (sandbox) or prod (real money). Derives the base URL.
KALSHI_API_KEY	(none)	Kalshi API key ID. Required only for authenticated tools.
KALSHI_PRIVATE_KEY_PATH	(none)	Path to your RSA private key .pem. Required for authenticated tools.
BASE_URL	(derived)	Optional explicit REST base override (must include /trade-api/v2).

See .env-example. Get API credentials at docs.kalshi.com/getting_started/api_keys and a demo account via the demo environment guide.

Claude Desktop (uvx)

"mcpServers": {
  "kalshi": {
    "command": "uvx",
    "args": ["mcp-server-kalshi"],
    "env": {
      "KALSHI_ENV": "demo",
      "KALSHI_API_KEY": "<YOUR KALSHI API KEY>",
      "KALSHI_PRIVATE_KEY_PATH": "PATH TO YOUR RSA KEY FILE"
    }
  }
}

Claude Desktop (Docker)

"mcpServers": {
  "kalshi": {
    "command": "docker",
    "args": ["run", "--rm", "-i",
      "--mount", "type=bind,src=/Users/username,dst=/Users/username",
      "-e", "KALSHI_ENV", "-e", "KALSHI_API_KEY", "-e", "KALSHI_PRIVATE_KEY_PATH",
      "mcp-server-kalshi"],
    "env": {
      "KALSHI_ENV": "demo",
      "KALSHI_API_KEY": "<YOUR KALSHI API KEY>",
      "KALSHI_PRIVATE_KEY_PATH": "PATH TO YOUR RSA KEY FILE"
    }
  }
}

Local Development

1. Create a .env file (see .env-example).
2. Install deps: uv sync (add --extra dev for dev tools). Requires Python 3.10+.
3. Run: uv run start.
4. Test: uv run pytest.

MCP Inspector

npx @modelcontextprotocol/inspector uv --directory /path/to/mcp-server-kalshi run start

Testing & code quality

uv sync --extra dev              # install dev tools (ruff, mypy, pytest, ...)
uv run pytest                    # run the test suite
uv run pytest --cov              # tests with a coverage report
uv run ruff check src tests      # lint
uv run black src tests           # format (add --check to verify only)
uv run mypy                      # type check
uv run pre-commit install        # (once) run ruff + black on every commit

Tests are pure/offline — they exercise the order translation and confirm-gate, the HTTP client (via an injected httpx.MockTransport), the MCP tool registry, config, and PDF extraction, all without touching the live Kalshi API. CI (.github/workflows/ci.yml) runs ruff + black + mypy + pytest across Python 3.10–3.13 on every push/PR, and releases are gated on that same suite.

Authentication

Requests are signed with RSA-PSS (MGF1-SHA256, max salt). Each authenticated request sends KALSHI-ACCESS-KEY, KALSHI-ACCESS-TIMESTAMP, and KALSHI-ACCESS-SIGNATURE, where the signed message is timestamp_ms + METHOD + path (path includes /trade-api/v2, excludes the query string).