Hebcal MCP Server provides a Model Context Protocol implementation for Jewish holidays and Hebrew calendar functionality. It allows you to generate Jewish holidays for any year and access the same powerful features available on the Hebcal website, including date conversion, Shabbat candle lighting times, and Torah readings.
To install the Hebcal MCP server, follow these steps:
npm install
npm run build
The MCP server can run in two different modes depending on your needs:
This is the default mode that communicates over standard input/output:
node build/cli.js
This mode communicates over HTTP using Server-Sent Events:
node build/server.js
By default, the SSE endpoint will be available at http://localhost:8080/mcp. You can configure the port using the NODE_PORT environment variable:
NODE_PORT=3000 node build/server.js
You can test the SSE endpoint using curl:
curl -N http://localhost:8080/mcp
For testing purposes, you would send MCP requests as JSON to the server. In stdio mode, you send them directly to the server's stdin. When using the SSE transport, you would need to implement an HTTP endpoint to receive requests, as the current implementation only handles outgoing messages.
To interact with the MCP server, you need to send properly formatted MCP requests. The server processes these requests and returns Jewish calendar data based on the parameters you provide.
For example, you can request Jewish holidays for a specific year, convert Hebrew and Gregorian dates, get Shabbat candle lighting times for a location, or look up Torah readings.
The server provides the same functionality as the Hebcal website's custom calendar tool but through a programmatic API that follows the Model Context Protocol.
To add this MCP server to Claude Code, run this command in your terminal:
claude mcp add-json "hebcal" '{"command":"node","args":["build/cli.js"]}'See the official Claude Code MCP documentation for more details.
There are two ways to add an MCP server to Cursor. The most common way is to add the server globally in the ~/.cursor/mcp.json file so that it is available in all of your projects.
If you only need the server in a single project, you can add it to the project instead by creating or adding it to the .cursor/mcp.json file.
To add a global MCP server go to Cursor Settings > Tools & Integrations and click "New MCP Server".
When you click that button the ~/.cursor/mcp.json file will be opened and you can add your server like this:
{
"mcpServers": {
"hebcal": {
"command": "node",
"args": [
"build/cli.js"
]
}
}
}To add an MCP server to a project you can create a new .cursor/mcp.json file or add it to the existing one. This will look exactly the same as the global MCP server example above.
Once the server is installed, you might need to head back to Settings > MCP and click the refresh button.
The Cursor agent will then be able to see the available tools the added MCP server has available and will call them when it needs to.
You can also explicitly ask the agent to use the tool by mentioning the tool name and describing what the function does.
To add this MCP server to Claude Desktop:
1. Find your configuration file:
~/Library/Application Support/Claude/claude_desktop_config.json%APPDATA%\Claude\claude_desktop_config.json~/.config/Claude/claude_desktop_config.json2. Add this to your configuration file:
{
"mcpServers": {
"hebcal": {
"command": "node",
"args": [
"build/cli.js"
]
}
}
}3. Restart Claude Desktop for the changes to take effect