Add one or more users to a Slack channel. Resolve emails to IDs first via lookup_user_by_email, then pass comma-separated IDs (max 1000). force=true (default) continues inviting valid users when some IDs are invalid.
AI agents use invite_user_to_channel 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 modifies Slack workspace state by adding users to channels, which is a Write operation (reversible data change). Severity is medium because while it affects channel membership and could grant unintended access, it can be reversed by removing users.
From the tool's definition The tool description states it will 'Add one or more users to a Slack channel,' which is a reversible modification operation that creates or changes group membership.
Documented attack patterns abuse exactly the kind of access invite_user_to_channel 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 invite_user_to_channel:
{
"version": "1",
"default": "deny",
"tools": {
"invite_user_to_channel": {
"limits": [
{
"counter": "invite_user_to_channel_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}invite_user_to_channel 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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Add one or more users to a Slack channel. Resolve emails to IDs first via lookup_user_by_email, then pass comma-separated IDs (max 1000). force=true (default) continues inviting valid users when some IDs are invalid. 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 invite_user_to_channel: 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.
invite_user_to_channel 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 invite_user_to_channel 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 invite_user_to_channel. 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.
invite_user_to_channel 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.
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423 Apple Shortcuts tools catalogued and risk-classified — across an index of 43,000+ MCP servers.