AI agents invoke mouse_button_down to trigger actions in Kwin. 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.
Based on the tool name and server context, this tool simulates pressing a mouse button down on a desktop GUI automation system. This is an Execute-level action as it triggers external operations (UI interactions) whose effects depend on arguments.
From the tool's definition Tool name 'mouse_button_down' on a server that automates Linux desktop GUI via Wayland; description is empty.
Documented attack patterns abuse exactly the kind of access mouse_button_down gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Kwin, and nothing reaches the server without passing your rules. This is the rule we recommend for mouse_button_down:
{
"version": "1",
"default": "deny",
"tools": {
"mouse_button_down": {
"limits": [
{
"counter": "mouse_button_down_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}mouse_button_down 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_button_down. It is categorised as a Execute tool in the Kwin MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Kwin MCP server in PolicyLayer and add a rule for mouse_button_down: 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 Kwin. Nothing to install.
mouse_button_down 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_button_down 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_button_down. 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_button_down is provided by the Kwin MCP server (isac322/kwin-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Kwin, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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30 Kwin tools catalogued and risk-classified — across an index of 43,000+ MCP servers.