cmux_send_panel · Cmux MCP: Risk & Policy

WHAT IT DOES

What cmux_send_panel does on Cmux

AI agents invoke cmux_send_panel to trigger actions in Cmux. 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.

WHY IT NEEDS A POLICY

Why cmux_send_panel needs a policy

Sending text into a terminal panel effectively executes arbitrary commands or input in that panel. The blast radius is high because an AI agent could send any shell command, script, or destructive input to an active terminal session in any workspace.

From the tool's definition 'Send text into an agent panel via send-panel' — sends arbitrary text/commands into a terminal pane, which executes whatever input is sent

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

cmux_send_panel Rate-limited

cmux_send_panel stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "cmux_send_panel": {
      "limits": [
        {
          "counter": "cmux_send_panel_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Cmux, so you can run agents against it safely.

FAQ

Questions about cmux_send_panel

What does the cmux_send_panel tool do? +

Send text into an agent panel via send-panel. Use cmux_list_panels to find the panel ref. Pass workspace/window when the panel lives in another workspace. It is categorised as a Execute tool in the Cmux MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on cmux_send_panel? +

Register the Cmux MCP server in PolicyLayer and add a rule for cmux_send_panel: 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 Cmux. Nothing to install.

What risk level is cmux_send_panel? +

cmux_send_panel is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit cmux_send_panel? +

Yes. Add a rate_limit block to the cmux_send_panel 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.

How do I block cmux_send_panel completely? +

Set action: deny in the PolicyLayer policy for cmux_send_panel. 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.

What MCP server provides cmux_send_panel? +

cmux_send_panel is provided by the Cmux MCP server (puchkoff/cmux-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.