AI agents call get_screen_size to retrieve information from Computer Control MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves system information (screen dimensions) with no side effects, making it a Read operation. The severity is low as knowing screen resolution poses minimal risk, though context matters—on a system where an AI agent has broad computer control capabilities (as evidenced by sibling tools like click_screen, drag_mouse, press_keys), even benign information retrieval could facilitate subsequent harmful…
From the tool's definition Tool name 'get_screen_size' and description 'Get the current screen resolution' indicate a query operation that retrieves display information without modifying state or triggering external actions.
Documented attack patterns abuse exactly the kind of access get_screen_size gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Computer Control MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for get_screen_size:
{
"version": "1",
"default": "deny",
"tools": {
"get_screen_size": {}
}
}get_screen_size is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get the current screen resolution. It is categorised as a Read tool in the Computer Control MCP MCP Server, which means it retrieves data without modifying state.
Register the Computer Control MCP server in PolicyLayer and add a rule for get_screen_size: 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 Computer Control MCP. Nothing to install.
get_screen_size 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 get_screen_size 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 get_screen_size. 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.
get_screen_size is provided by the Computer Control MCP server (ab498/computer-control-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 15 Computer Control MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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15 Computer Control MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.