Schedule a message to be posted at a future time. post_at is a Unix timestamp in SECONDS (not ms). Max 30 scheduled messages per channel per 5 minutes. Max 120 days in advance.
AI agents use schedule_slack_message to create or update resources in Apple Shortcuts — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Apple Shortcuts environment.
This tool creates a new scheduled message in Slack, which is a Write operation—reversible data creation. It does not execute code, delete data, move money, or trigger arbitrary external operations.
From the tool's definition Tool description explicitly states 'Schedule a message to be posted at a future time' and references posting constraints ('Max 30 scheduled messages per channel per 5 minutes. Max 120 days in advance'). The word 'posted' confirms message creation/modification.
Documented attack patterns abuse exactly the kind of access schedule_slack_message gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Apple Shortcuts, and nothing reaches the server without passing your rules. This is the rule we recommend for schedule_slack_message:
{
"version": "1",
"default": "deny",
"tools": {
"schedule_slack_message": {
"limits": [
{
"counter": "schedule_slack_message_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}schedule_slack_message stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Schedule a message to be posted at a future time. post_at is a Unix timestamp in SECONDS (not ms). Max 30 scheduled messages per channel per 5 minutes. Max 120 days in advance. It is categorised as a Write tool in the Apple Shortcuts MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Apple Shortcuts MCP server in PolicyLayer and add a rule for schedule_slack_message: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Apple Shortcuts. Nothing to install.
schedule_slack_message is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the schedule_slack_message rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for schedule_slack_message. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
schedule_slack_message is provided by the Apple Shortcuts MCP server (@mindstone/mcp-server-apple-shortcuts). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Apple Shortcuts, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
423 Apple Shortcuts tools catalogued and risk-classified — across an index of 43,000+ MCP servers.