Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add JayRHa/AgentSkills --skill cron-schedulergit clone --depth 1 https://github.com/JayRHa/AgentSkillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/jayrha/agentskills/cron-scheduler)<a href="https://agentmods.dev/skills/jayrha/agentskills/cron-scheduler"><img src="https://agentmods.dev/badge/skills/jayrha/agentskills/cron-scheduler/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/jayrha/agentskills/cron-scheduler"><img src="https://agentmods.dev/badge/skills/jayrha/agentskills/cron-scheduler.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00137 | $0.01995 |
| Opus 5.5 | $0.00055 | $0.00798 |
| Sonnet 5.5 | $0.00027 | $0.00399 |
| Haiku 4.5 | $0.00014 | $0.00199 |
Grade A, and why
cron-scheduler scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 82 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Cron Scheduler
Overview
Translate human scheduling intent into correct cron expressions, explain existing expressions in plain language, preview the next fire times, and avoid the subtle traps (DOM/DOW OR-logic, timezone/DST drift, overlapping long-running jobs, missed runs on downtime). Covers classic Vixie/POSIX cron, plus the dialects used by systemd timers, Quartz, AWS EventBridge, Kubernetes CronJobs, and GitHub Actions.
Keywords: cron, crontab, cron expression, schedule, scheduler, scheduled job, */5, 0 9 * * 1-5, timezone, TZ, DST, daylight saving, day-of-week, day-of-month, systemd timer, OnCalendar, Quartz, EventBridge rate/cron, Kubernetes CronJob, GitHub Actions schedule, every N minutes, weekday, next run, overlap, concurrencyPolicy, flock.
Workflow
- Identify the target system. Cron dialects differ. Ask or infer: classic crontab (5 fields), systemd
OnCalendar, Quartz/Spring (6-7 fields with seconds +?), AWS EventBridge (6 fields, year, requires?), Kubernetes CronJob (5 fields, UTC by default), or GitHub Actions (5 fields, UTC only). Seereferences/cron-syntax.mdfor the field tables per dialect. - Pin down the timezone. Determine where the schedule should fire in wall-clock terms and which TZ the runner uses. Most engines run in UTC or the daemon's local TZ — not the user's. Decide and state explicitly. See
references/timezones-and-dst.md. - Build the expression field by field using
references/cron-syntax.md. Prefer ranges and steps (9-17,*/15) over enumerations when they read clearly. - Check the OR-logic trap. If BOTH day-of-month and day-of-week are restricted (neither is
*), Vixie cron fires when EITHER matches, not both. This is the #1 silent bug. See the worked example inexamples/build-and-explain.md. - Validate and preview. Run
scripts/cronlint.py "<expr>" -n 5to confirm it parses, see a plain-language breakdown, and list the next fire times. Always preview before delivering. - Audit operational pitfalls: DST gaps/doubles, jobs slower than their interval (overlap), missed runs after downtime, and the difference between "every 5 minutes" and "every hour at minute 5." See
references/scheduling-pitfalls.md. - Deliver the expression, a one-line plain-English explanation, the assumed timezone, and the next 3-5 fire times.
What ships with it
5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 82 lines · 137 tokens per session scan A 686e020d4296
cron-scheduler is a skill published in the GitHub repository JayRHa/AgentSkills (12 stars, last pushed 2mo ago), licensed MIT. It adds 137 tokens to every session and 1,995 once invoked, about $0.0005 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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