AI agents call Visible to retrieve information from OfficeMCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool only checks/queries whether Excel is visible on screen. It performs a non-destructive read operation with no capability to modify, delete, or execute actions. The low severity reflects minimal blast radius—an AI agent cannot cause harm by checking visibility status.
From the tool's definition Tool name 'Visible' and description 'Check if the microsoft excel application is visible' indicate a query operation that retrieves application visibility state with no side effects.
Documented attack patterns abuse exactly the kind of access Visible gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and OfficeMCP, and nothing reaches the server without passing your rules. This is the rule we recommend for Visible:
{
"version": "1",
"default": "deny",
"tools": {
"Visible": {}
}
}Visible is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Check if the microsoft excel application is visible. It is categorised as a Read tool in the OfficeMCP MCP Server, which means it retrieves data without modifying state.
Register the Office MCP server in PolicyLayer and add a rule for Visible: 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 OfficeMCP. Nothing to install.
Visible 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 Visible 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 Visible. 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.
Visible is provided by the Office MCP server (officemcp/officemcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 16 OfficeMCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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16 OfficeMCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.