Server data from the Official MCP Registry
MCP cron validator for AI agents; flags impossible schedules and other silent cron bugs.
About
MCP cron validator for AI agents; flags impossible schedules and other silent cron bugs.
Security Report
This is a well-engineered cron expression parser MCP server with clean architecture, no authentication requirements (appropriate for its stateless utility purpose), and zero dangerous patterns. The codebase is battle-tested (638-line engine with 69 unit tests), zero-dependency core, and has proper error handling. Minor code quality observations do not materially affect security posture. Supply chain analysis found 1 known vulnerability in dependencies (0 critical, 1 high severity). Package verification found 1 issue.
6 files analyzed · 6 issues found
Security scores are indicators to help you make informed decisions, not guarantees. Always review permissions before connecting any MCP server.
Permissions Required
This plugin requests these system permissions. Most are normal for its category.
How to Install
Add this to your MCP configuration file:
{
"mcpServers": {
"io-github-takeaseatventure-cron-mcp": {
"args": [
"-y",
"cron-mcp-server"
],
"command": "npx"
}
}
}Documentation
View on GitHubFrom the project's GitHub README.
cron-mcp
An MCP (Model Context Protocol) server that lets AI coding agents — Claude, Cursor, Copilot, Cline — parse, validate, explain, and preview cron expressions.
Built to catch silent cron bugs (impossible schedules, OR-semantics gotchas, midnight spikes) before a job is deployed — a class of mistake that's easy to make and hard to notice until a critical job silently fails to fire.
Why
Cron expressions are deceptively tricky. Common silent failures:
0 0 30 2 *→ never runs (February has no 30th). Syntactically valid, semantically dead.0 0 1,15 * 1→ fires on the 1st OR 15th OR Monday, not "the 1st and 15th if Monday" (the classic dom+dow OR-semantics trap).*/7 * * * *→ uneven step; intervals drift (:00, :07, :14, …, :56, :00— not "every 7 minutes" cleanly).0 0 * * *→ midnight spike; every job in the system competes at 00:00.
cron-mcp surfaces these as warnings, observations, and suggestions that the AI agent can act on — before you ship the schedule.
Tools exposed
| Tool | Description |
|---|---|
parse_cron | Parse a cron expression → plain-English description of when it fires. Supports 5-field standard cron + L (last), W (nearest weekday), # (nth weekday), named months/days. |
validate_cron | Deep validation: impossible schedules, OR-semantics, midnight spikes, uneven steps, leap-year edges, frequency estimate (~runs/year). |
next_runs | Compute the next N fire times as ISO-8601 + relative offsets. |
cron_presets | Library of common, proven schedules (every 5 min, hourly, weekdays 9am, monthly, quarterly, …). |
Install
npm install -g cron-mcp-server
Published links
- npm package — installable release
0.1.2 - Official MCP Registry — registry record
- GitHub release — downloadable source checkpoint
Configure
Claude Desktop
Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or the equivalent on your OS:
{
"mcpServers": {
"cron": {
"command": "cron-mcp-server",
"args": []
}
}
}
Cursor
Add to .cursor/mcp.json (or ~/.cursor/mcp.json for global):
{
"mcpServers": {
"cron": {
"command": "cron-mcp-server"
}
}
}
VS Code (Copilot)
{
"mcp.servers": {
"cron": {
"type": "stdio",
"command": "cron-mcp-server"
}
}
}
Direct (no install)
npx cron-mcp-server
Example usage
Once connected, just ask the agent in natural language:
- "Validate this cron:
0 0 30 2 *" - "When does
*/5 * * * *next fire?" - "Give me a cron for every weekday at 9am"
- "Is there anything risky about
0 0 1,15 * 1?"
The agent calls the tools and returns structured, actionable results.
Engine
The cron engine is battle-tested: 638 lines, zero dependencies, originally extracted from a browser-based cron generator and hardened with 69 unit tests. This MCP server is a thin tool wrapper around it.
License
MIT © takeaseatventure
Reviews
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