Clear browser state to create a clean replay environment for the currently selected page. This clears cookies that affect the current page
AI agents call clear_site_data to permanently remove resources in JS Reverse MCP — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Although the tool targets only the currently selected page and is framed as creating a 'clean replay environment,' clearing cookies is a destructive operation—the deleted state cannot be programmatically restored. If an agent accidentally targets the wrong page or clears data for an authenticated session, recovery requires manual re-login or external cookie restoration.
From the tool's definition clear_site_data clears cookies and browser state irreversibly for the current page. Cookies cannot be recovered once deleted, and this action cannot be undone without external intervention (e.g., re-authentication).
Attacks that exploit this kind of access
Clear browser state to create a clean replay environment for the currently selected page. This clears cookies that affect the current page. It is categorised as a Destructive tool in the JS Reverse MCP MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the JS Reverse MCP server in PolicyLayer and add a rule for clear_site_data: 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 JS Reverse MCP. Nothing to install.
clear_site_data is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the clear_site_data 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 clear_site_data. 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.
clear_site_data is provided by the JS Reverse MCP server (zhizhuodemao/js-reverse-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.