AI agents call browser_extract_data 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 queries and retrieves information from a browser page's DOM, converting it to JSON format. It performs no mutations, deletions, code execution, or external state changes. It is a Read operation analogous to a GET request or data fetch. The low severity reflects minimal blast radius—misuse would only expose information already visible in the browser context.
From the tool's definition Tool name and description: 'Extract structured data from the page (tables, lists, repeated items) as JSON.' The verb 'extract' and the passive framing of reading data from an already-loaded page indicate pure data retrieval with no side effects.
Attacks that exploit this kind of access
Extract structured data from the page (tables, lists, repeated items) as JSON. 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_extract_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 Wmux. Nothing to install.
browser_extract_data 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_extract_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 browser_extract_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.
browser_extract_data 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_extract_data 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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