Manage localStorage or sessionStorage: get, set, or clear. Reads on sensitive pages (email, banking, auth) are blocked unless allowSensitiveDomains:true is set.
AI agents call browser_storage to permanently remove resources in Wmux — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
An AI agent that decides to call browser_storage doesn't hesitate, doesn't double-check, and doesn't stop at one. Whatever it removes from Wmux is gone — there is no undo for destructive operations.
Attacks that exploit this kind of access
Manage localStorage or sessionStorage: get, set, or clear. Reads on sensitive pages (email, banking, auth) are blocked unless allowSensitiveDomains:true is set. It is categorised as a Destructive tool in the Wmux MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Wmux MCP server in PolicyLayer and add a rule for browser_storage: 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 Wmux. Nothing to install.
browser_storage 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 browser_storage 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 browser_storage. 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.
browser_storage is provided by the Wmux MCP server (openwong2kim/wmux). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
browser_storage is one line of Wmux's registry record.
The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.
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