io.github.assymetrix/mcp-server

Assymetrix agent tools

Prediction market data from Polymarket, Kalshi and Limitless for AI agents, from the Assymetrix Data API:

• @assymetrix/mcp-server: an MCP server with three read-only tools, in packages/mcp-server.
• prediction-market-data: an Agent Skill that teaches an agent to use the same API with curl, in skills/prediction-market-data.
• A Claude Code plugin that bundles both (.claude-plugin/).

Everything here only reads market data. Nothing places orders, moves money or links wallets, and nothing here is financial advice. You use your own Assymetrix API key, and a free key works.

Get an API key

1. Create a free account at https://dashboard.assymetrix.com/signup?utm_source=github&utm_campaign=agent-tools
2. Open API Keys and create a key. It is shown once and starts with asy_.
3. Keep it in an environment variable, for example in your shell profile: export ASSYMETRIX_API_KEY=asy_...

The Free plan includes 10,000 requests per rolling 30 days, 1 request per second and 30 days of history. Each tool call is one request. Paid plans: https://dashboard.assymetrix.com/billing

Install

Recommended: the Claude Code plugin (MCP server and skill)

/plugin marketplace add assymetrix/assymetrix-agent-tools
/plugin install assymetrix@assymetrix

Claude Code asks for your API key when you enable the plugin and keeps it in your system's secure store, so the key never sits in a config file or the chat.

Other clients

These read the key from an environment variable or their own config file. Keep the key in your shell profile (export ASSYMETRIX_API_KEY=asy_...) rather than typing it into a command.

Claude Code without the plugin (--transport goes before the name):

claude mcp add --env ASSYMETRIX_API_KEY="$ASSYMETRIX_API_KEY" --transport stdio assymetrix -- npx -y @assymetrix/mcp-server

Codex:

codex mcp add assymetrix --env ASSYMETRIX_API_KEY="$ASSYMETRIX_API_KEY" -- npx -y @assymetrix/mcp-server

Cursor (~/.cursor/mcp.json or .cursor/mcp.json):

{
  "mcpServers": {
    "assymetrix": {
      "command": "npx",
      "args": ["-y", "@assymetrix/mcp-server"],
      "env": { "ASSYMETRIX_API_KEY": "${env:ASSYMETRIX_API_KEY}" }
    }
  }
}

Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "assymetrix": {
      "command": "npx",
      "args": ["-y", "@assymetrix/mcp-server"],
      "env": { "ASSYMETRIX_API_KEY": "asy_..." }
    }
  }
}

VS Code (.vscode/mcp.json, which asks for the key and hides it):

{
  "inputs": [
    {
      "type": "promptString",
      "id": "assymetrix-key",
      "description": "Assymetrix API key",
      "password": true
    }
  ],
  "servers": {
    "assymetrix": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@assymetrix/mcp-server"],
      "env": { "ASSYMETRIX_API_KEY": "${input:assymetrix-key}" }
    }
  }
}

Skill only (Claude Code, Codex, Cursor and other agents)

npx skills add assymetrix/assymetrix-agent-tools

The skill reads ASSYMETRIX_API_KEY from the agent's environment and never prints it.

Tools

Prices are probabilities from 0 to 1. How far back history goes depends on your plan; when your plan cuts a range, the result says so.

Configuration

Privacy

• The MCP server talks only to the Assymetrix Data API, sending your key in the x-api-key header, a User-Agent with its version, and a random request id that support can use to find a call.
• It collects no telemetry, writes nothing to disk, and never logs or returns your key.
• The skill runs curl against the same API from your own machine.
• Privacy policy: https://www.assymetrix.com/privacy-policy. Support: support@assymetrix.com.

Development

cd packages/mcp-server
pnpm install
pnpm run check      # type check, build, then the tests (no network)
node ../../skills/validate-skill.cjs ../../skills/prediction-market-data            # skill format checks
node ../../skills/validate-skill.cjs ../../skills/prediction-market-data --release  # also fails on open TODO markers

License

MIT