cmux_raw · Cmux MCP: Risk & Policy

WHAT IT DOES

What cmux_raw does on Cmux

AI agents invoke cmux_raw 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_raw needs a policy

This tool is an unrestricted escape hatch that passes arbitrary tokens to the cmux CLI. Since cmux controls terminal panes, workspaces, input, and browser, arbitrary subcommands could execute shell commands, destroy workspaces, send malicious input, or perform any other action supported by the CLI.

From the tool's definition 'Escape hatch for cmux subcommands without a dedicated tool. Pass tokens after' — allows arbitrary cmux subcommand execution without restriction

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

cmux_raw Rate-limited

cmux_raw 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_raw": {
      "limits": [
        {
          "counter": "cmux_raw_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_raw

What does the cmux_raw tool do? +

Escape hatch for cmux subcommands without a dedicated tool. Pass tokens after. 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_raw? +

Register the Cmux MCP server in PolicyLayer and add a rule for cmux_raw: 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_raw? +

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

Can I rate-limit cmux_raw? +

Yes. Add a rate_limit block to the cmux_raw 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_raw completely? +

Set action: deny in the PolicyLayer policy for cmux_raw. 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_raw? +

cmux_raw 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.