Cron Explainer

Requirements

• Python 3.11 or newer
• No API keys
• No configuration
• No network access
• No environment variables

The only runtime dependency is the official MCP Python SDK. Everything else is the standard library: zoneinfo, datetime, calendar, re and dataclasses. The cron engine is implemented here rather than pulled from croniter or dateutil, which keeps the supply chain empty and the behaviour inspectable.

On Windows, zoneinfo has no system timezone database, so install tzdata alongside it (pip install tzdata). Linux and macOS already have one.

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Install and run

Pick whichever suits you. uvx needs no install step at all:

uvx cron-explainer

pipx install cron-explainer
cron-explainer

git clone https://github.com/cryptobyte/cron-explainer
cd cron-explainer
pip install -e .
cron-explainer

The server speaks MCP over stdio, so running it by hand just leaves it waiting for a client on stdin. That is expected. Use cron-explainer --version to check the install.

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Client configuration

Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "cron-explainer": {
      "command": "uvx",
      "args": ["cron-explainer"]
    }
  }
}

Claude Code:

claude mcp add cron-explainer -- uvx cron-explainer

Cursor (.cursor/mcp.json):

{
  "mcpServers": {
    "cron-explainer": {
      "command": "uvx",
      "args": ["cron-explainer"]
    }
  }
}

VS Code (.vscode/mcp.json):

{
  "servers": {
    "cron-explainer": {
      "type": "stdio",
      "command": "uvx",
      "args": ["cron-explainer"]
    }
  }
}

If you installed with pipx or pip instead of using uvx, replace the command with cron-explainer and drop the args.