Stop an ongoing call immediately. WHEN TO USE: - User wants to end a call in progress - Call is stuck or behaving unexpectedly - Emergency stop COMMON MISTAKES: - Calling this on an already ended call; use get_call first if unsure ERROR RECOVERY: - 401: API key is missing or invalid → configure_r...
AI agents invoke stop_call to trigger actions in Apple Shortcuts. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
This tool executes an external operation (stopping an active call) whose effects depend on which call_id is targeted. It is not a Read operation (it modifies state), not Write (changes are not reversible - a terminated call cannot be un-terminated), and not Destructive (it doesn't delete data, but rather terminates a process). It is Execute because it triggers an immediate action on an external system.
From the tool's definition Tool description states 'Stop an ongoing call immediately' with use cases including 'end a call in progress' and 'Emergency stop'. The tool performs an immediate action that terminates an active external operation (a phone/voice call).
Documented attack patterns abuse exactly the kind of access stop_call 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 stop_call:
{
"version": "1",
"default": "deny",
"tools": {
"stop_call": {
"limits": [
{
"counter": "stop_call_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}stop_call stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Stop an ongoing call immediately. WHEN TO USE: - User wants to end a call in progress - Call is stuck or behaving unexpectedly - Emergency stop COMMON MISTAKES: - Calling this on an already ended call; use get_call first if unsure ERROR RECOVERY: - 401: API key is missing or invalid → configure_retell_api_key - 404: call_id not found or no longer active → verify with list_calls/get_call RELATED TOOLS: - get_call: Check whether status is. It is categorised as a Execute tool in the Apple Shortcuts MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Apple Shortcuts MCP server in PolicyLayer and add a rule for stop_call: 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.
stop_call is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the stop_call 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 stop_call. 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.
stop_call 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.