AI agents call surface_list 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 retrieves metadata about existing terminals and browsers (surfaceId, ptyId, shell, CWD, git branch) without creating, modifying, deleting, or executing anything. It is a pure information-retrieval operation. The blast radius if misused is low—exposing workspace surface information is a disclosure risk but not destructive or executable.
From the tool's definition Tool name 'surface_list' and description 'List all surfaces (terminals and browsers) in a workspace. Returns surfaceId, ptyId, shell, CWD, git branch for each surface.' — explicitly a read/query operation with no modification or side effects.
Attacks that exploit this kind of access
List all surfaces (terminals and browsers) in a workspace. Returns surfaceId, ptyId, shell, CWD, git branch for each surface. Omit workspaceId to list your own workspace. 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 surface_list: 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.
surface_list 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 surface_list 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 surface_list. 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.
surface_list 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.
surface_list 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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