AI agents call list_windows to retrieve information from Mac without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool retrieves information about currently visible windows (app name, title, position, size) without modifying, executing, or deleting anything. The optional filter parameter is purely for scoping the read. No system state changes occur. This is a standard information retrieval operation.
From the tool's definition Tool name 'list_windows' and description 'Lists all visible windows' — this is a query/retrieval operation with no side effects.
Attacks that exploit this kind of access
Lists all visible windows with app name, title, position, and size. Optional: filter by app name. It is categorised as a Read tool in the Mac MCP Server, which means it retrieves data without modifying state.
Register the Mac MCP server in PolicyLayer and add a rule for list_windows: 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 Mac. Nothing to install.
list_windows is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the list_windows 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 list_windows. 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.
list_windows is provided by the Mac MCP server (laststance/mac-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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