Connect Claude Desktop

Configure Claude Desktop to use the Alphacast MCP server via npx.

Claude Desktop launches MCP servers as local processes defined in claude_desktop_config.json. The Alphacast MCP server runs via npx and communicates over stdio.

Configuration file location

OS	Path
macOS	~/Library/Application Support/Claude/claude_desktop_config.json
Windows	%APPDATA%\Claude\claude_desktop_config.json
Linux	~/.config/Claude/claude_desktop_config.json

If the file does not exist, create it with an empty {} and add the snippet below.

Add the server

claude_desktop_config.json

{
  "mcpServers": {
    "alphacast": {
      "command": "npx",
      "args": ["-y", "@alphacast/mcp"],
      "env": {
        "ALPHACAST_API_KEY": "YOUR_API_KEY"
      }
    }
  }
}

npx ships with Node.js. If npx is not found, install Node 18 or later from nodejs.org and try again.

Apply the change

1. Save claude_desktop_config.json.
2. Quit Claude Desktop completely (right-click the menu bar / system tray icon → Quit, not just close the window).
3. Relaunch Claude Desktop.

Verify

In a new chat, open the tools menu (the slider icon). You should see the alphacast server listed with its 32 tools enabled. Try:

“List my Alphacast repositories.”

If the tools menu shows a red dot or the server is missing, open Claude Desktop’s Developer → Open MCP Logs menu to inspect the failure. The most common causes are an invalid ALPHACAST_API_KEY or Node.js not being on the system PATH.