AI agents call check_cookies to retrieve information from N Lobby MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool only reads and validates authentication state (checks if cookies exist) without retrieving sensitive user data, modifying anything, or executing operations. It is purely informational. Severity is low because misuse would only expose whether a session is authenticated, not confidential school data or trigger destructive actions.
From the tool's definition Tool name is 'check_cookies' and description states it 'Check if authentication cookies are set' — a query operation that verifies the presence of cookies without modifying data or triggering side effects.
Documented attack patterns abuse exactly the kind of access check_cookies gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and N Lobby MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for check_cookies:
{
"version": "1",
"default": "deny",
"tools": {
"check_cookies": {}
}
}check_cookies 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 authentication cookies are set. It is categorised as a Read tool in the N Lobby MCP Server MCP Server, which means it retrieves data without modifying state.
Register the N Lobby MCP Server MCP server in PolicyLayer and add a rule for check_cookies: 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 N Lobby MCP Server. Nothing to install.
check_cookies 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 check_cookies 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 check_cookies. 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.
check_cookies is provided by the N Lobby MCP Server MCP server (minagishl/nlobby-cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from N Lobby MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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28 N Lobby MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.