Stop the notification watcher.
AI agents invoke stop_watcher to trigger actions in Openowl. 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.
Stopping a watcher constitutes executing an external operation that modifies system state by halting an ongoing service. While not destructive (reversible by restarting), it is an Execute action that triggers external effects on the target system. The blast radius is medium because disabling notification monitoring could disrupt expected system behavior or workflows dependent on that watcher.
From the tool's definition Tool name is 'stop_watcher' and description states 'Stop the notification watcher.' This terminates an active monitoring process on the desktop.
Documented attack patterns abuse exactly the kind of access stop_watcher gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Openowl, and nothing reaches the server without passing your rules. This is the rule we recommend for stop_watcher:
{
"version": "1",
"default": "deny",
"tools": {
"stop_watcher": {
"limits": [
{
"counter": "stop_watcher_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}stop_watcher 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 the notification watcher. It is categorised as a Execute tool in the Openowl MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Openowl MCP server in PolicyLayer and add a rule for stop_watcher: 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 Openowl. Nothing to install.
stop_watcher 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_watcher 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_watcher. 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_watcher is provided by the Openowl MCP server (mihir-kanzariya/openowl). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Openowl, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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40 Openowl tools catalogued and risk-classified — across an index of 43,000+ MCP servers.