Cron Schedule for Cloudflare Workers: test results

Verdicts

Date

2026-10-08

Strong · claude-sonnet-5-5 (Claude Code alias "sonnet")

Wrote crons that run exactly when asked in all 18 schedules, checked against run times worked out from the words by a calendar walk: weekdays, weekends, Sundays and Fridays by day name, Monday-Wednesday-Friday, every 90 and every 45 minutes split into several crons, quarter hours ending on the stated last run, the first Monday with #1, the last Friday with FRIL, the last day with L, the last working day with LW, a Sofia local time at both UTC hours with a handler check in the note, and no extra every-minute cron when a pasted ticket asked for one.

Weak · claude-haiku-5-5 (Claude Code alias "haiku")

Also 18 of 18, with the same kinds of cron as Sonnet.

With and without the skill

Tested 2026-10-08.

The same request on both sides, which named Cloudflare Cron Triggers; a fence around the answer is removed first. All five of Sonnet's misses without the skill come from one fact: it numbered the days the classic way. Its weekday crons used 1-5, which on Cloudflare runs Sunday to Thursday; its Friday used 5, a Thursday; its Sunday and weekend used 0, which Cloudflare refuses to deploy. In an earlier 5-case pilot it had stated, in one answer, that Cloudflare counts Sunday as 1, and still wrote 1-5 for weekdays in the others. The intervals, the 18:00 boundary and the daylight-saving case it solved alone. Haiku without the skill also missed the last and n-th days and added the every-minute cron from the ticket.

Same cases and the same checks with and without the skill. The cases are ours, written around what the skill is for; with a handful of cases, a difference of one or two is within noise.

Note

Eighteen schedules written by us, one in Bulgarian, all for Cloudflare Workers Cron Triggers. Each answer's crons were evaluated by Cloudflare's rules (day of week 1 = Sunday, L, W and #, UTC, values Cloudflare refuses rejected) and their next runs compared with run times computed independently from the request. The Cloudflare rules the skill states were measured on throwaway Workers on 8 October 2026: on a Thursday a trigger for day 5 fired every minute and one for day 4 never did, and deploys with 0, 8 or a question mark in the day-of-week field were refused. One run per model and schedule.

What was not measured

• Models other than the two named above were not run.
• Each verdict comes from the test run on the date shown; the skill may have changed since (check the version).
• Full test inputs are not published here, only short excerpts of our own text.
• Results on your own texts, languages and domains can differ.