AI agents invoke terminal_send 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.
Sending text to a terminal can trigger arbitrary command execution depending on what text is sent and what is already running in the terminal. Even without auto-pressing Enter, it places potentially dangerous input into a shell or interactive process. The blast radius is high because an AI agent could craft inputs that execute system commands, modify files, or exfiltrate data.
From the tool's definition "Send text to a terminal" — sends input to a live terminal session, which can run shell commands or interact with TUI applications
Attacks that exploit this kind of access
Send text to a terminal. By default the text is written as-is — no Enter is pressed, so a shell command or TUI chat prompt will sit on the input line without being committed. Pass. 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 terminal_send: 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.
terminal_send 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 terminal_send 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 terminal_send. 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.
terminal_send 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.
terminal_send 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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