AI agents call browser_snapshot to retrieve information from Wmux without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool reads and returns page structure data without side effects. It captures the current DOM state as text for analysis, similar to a get or fetch operation. No data is written, deleted, or executed; no external effects are triggered beyond querying the current page state. The low severity reflects that snapshots pose minimal risk even if misused by an agent.
From the tool's definition Tool description states it 'Take[s] an accessibility tree snapshot' and 'Returns a text representation' — retrieval and inspection only, no modification or action performed on the page.
Attacks that exploit this kind of access
Take an accessibility tree snapshot of the current page. Returns a text representation of the page structure with interactive elements annotated with ref numbers. It is categorised as a Read tool in the Wmux MCP Server, which means it retrieves data without modifying state.
Register the Wmux MCP server in PolicyLayer and add a rule for browser_snapshot: 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_snapshot 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 browser_snapshot 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_snapshot. 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_snapshot 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_snapshot 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.
Teams ship this data inside their own products. See what a licence covers →