cmux_notify · Cmux MCP: Risk & Policy

WHAT IT DOES

What cmux_notify does on Cmux

AI agents invoke cmux_notify 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_notify needs a policy

Triggering a notification is an external operation that causes a side effect in the terminal/UI environment. It doesn't purely read data, but it also isn't writing persistent data. It executes an action (displaying a notification via the cmux CLI). The blast radius is low since misuse at most causes spurious notifications.

From the tool's definition Show a cmux notification

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

cmux_notify Rate-limited

cmux_notify 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_notify": {
      "limits": [
        {
          "counter": "cmux_notify_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_notify

What does the cmux_notify tool do? +

Show a cmux notification. 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_notify? +

Register the Cmux MCP server in PolicyLayer and add a rule for cmux_notify: 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_notify? +

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

Can I rate-limit cmux_notify? +

Yes. Add a rate_limit block to the cmux_notify 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_notify completely? +

Set action: deny in the PolicyLayer policy for cmux_notify. 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_notify? +

cmux_notify 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.