AI agents invoke mouse_down to trigger actions in GNOME Desktop MCP. 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 injects a mouse button press event into the desktop environment. It executes a hardware-level input action with real side effects — it can trigger UI interactions, drag operations, or other desktop actions depending on what is under the cursor.
From the tool's definition Press mouse button down without releasing
Documented attack patterns abuse exactly the kind of access mouse_down gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and GNOME Desktop MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for mouse_down:
{
"version": "1",
"default": "deny",
"tools": {
"mouse_down": {
"limits": [
{
"counter": "mouse_down_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}mouse_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.
Free to start. No card required.
Press mouse button down without releasing. It is categorised as a Execute tool in the GNOME Desktop MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the GNOME Desktop MCP server in PolicyLayer and add a rule for mouse_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 GNOME Desktop MCP. Nothing to install.
mouse_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_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_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_down is provided by the GNOME Desktop MCP server (sbuysse/gnome-desktop-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from GNOME Desktop MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
30 GNOME Desktop MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.