AI agents invoke browser_wait_for_download to trigger actions in Wmux. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
This tool executes a browser automation command that waits for and processes download events. While it does not directly delete or create persistent data on the host system (ruling out Destructive/Write), it monitors and potentially triggers file acquisition from external sources. The action is reversible but has side effects that depend on the download context.
From the tool's definition Tool name 'browser_wait_for_download' and description 'Wait for a download event on the page' indicate it monitors and triggers browser automation actions that initiate external side effects (file downloads).
Attacks that exploit this kind of access
Wait for a download event on the page. Optionally filter by filename. It is categorised as a Execute tool in the Wmux MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Wmux MCP server in PolicyLayer and add a rule for browser_wait_for_download: 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_wait_for_download is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the browser_wait_for_download 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_wait_for_download. 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_wait_for_download 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_wait_for_download 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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