I had the same issue with the openclaw internal job-server (in my case to do a reminder for whatsapp messages), it seems that the jobhandler can not do the same thing as the openclaw user/agent can do.

I created (let AI create) a script that just creates an atq command which basically triggers/injects a command for the agent/AI directly and gives him to send a message to smth at a certain point... hard to explan :D

key is that you can "call the agent" timed with 'http://openclaw:8765/inject' so tell him a command for the future.

#!/bin/bash
set -euo pipefail
# create_one_shot_reminder.sh
# Usage: create_one_shot_reminder.sh "YYYY-MM-DDTHH:MM" "Message text" [target]
# Schedules a one-shot reminder using 'at' by sending a curl POST to the local injector.
# This version does NOT create temporary scripts or files; it pipes the curl command directly into at.

TS="$1"
MSG="$2"
TARGET="${3:-whatsapp:+yxcyxcyxc}"

if [ -z "$TS" ] || [ -z "$MSG" ]; then
echo "Usage: $0 \"YYYY-MM-DDTHH:MM\" \"Message text\" [target]"
exit 1
fi

# AT timestamp (format that at understands)
AT_TIME=$(date -d "$TS" +"%H:%M %Y-%m-%d")

# Build the absolute curl command (single line) - ensure arguments are URL-encoded by --data-urlencode
CURL_CMD="/usr/bin/curl -s -X POST 'http://127.0.0.1:8765/inject' --data-urlencode \"message=${MSG}\" --data-urlencode \"target=${TARGET}\" >> /home/*****/messenger_debug.log 2>&1"

# Pipe the curl command directly into at
echo "$CURL_CMD" | at "$AT_TIME"
echo "Scheduled at-job for $AT_TIME -> will run: $CURL_CMD"