AI agents invoke mouse_up to trigger actions in PyMCPAutoGUI. 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.
On a GUI automation server, 'mouse_up' almost certainly releases a mouse button, which is a direct desktop interaction/execution action. Combined with other tools like click and drag, it can trigger arbitrary GUI operations. Severity is high because GUI automation can affect any application on the desktop. Confidence is moderate due to the empty description.
From the tool's definition Tool name 'mouse_up' on a GUI automation server described as allowing agents to 'control mouse, keyboard, windows'. Empty description lowers confidence.
Documented attack patterns abuse exactly the kind of access mouse_up gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and PyMCPAutoGUI, and nothing reaches the server without passing your rules. This is the rule we recommend for mouse_up:
{
"version": "1",
"default": "deny",
"tools": {
"mouse_up": {
"limits": [
{
"counter": "mouse_up_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}mouse_up 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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mouse_up. It is categorised as a Execute tool in the PyMCPAutoGUI MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the PyMCPAutoGUI MCP server in PolicyLayer and add a rule for mouse_up: 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 PyMCPAutoGUI. Nothing to install.
mouse_up 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 mouse_up 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 mouse_up. 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.
mouse_up is provided by the PyMCPAutoGUI MCP server (kitfactory/pymcpautogui). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from PyMCPAutoGUI, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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34 PyMCPAutoGUI tools catalogued and risk-classified — across an index of 43,000+ MCP servers.