tmux_create_window · Tmux MCP: Risk & Policy

WHAT IT DOES

What tmux_create_window does on Tmux

AI agents invoke tmux_create_window to trigger actions in Tmux. 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 tmux_create_window needs a policy

Creating a tmux window is an execution-level operation that spawns a new shell/process environment within a session. While it doesn't run arbitrary commands directly, it sets up an interactive execution context that can be used to run commands. It modifies the tmux session state but is reversible (windows can be killed), so it doesn't reach Destructive level.

From the tool's definition "Create a new window in an existing tmux session"

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

tmux_create_window Rate-limited

tmux_create_window 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": {
    "tmux_create_window": {
      "limits": [
        {
          "counter": "tmux_create_window_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 Tmux, so you can run agents against it safely.

FAQ

Questions about tmux_create_window

What does the tmux_create_window tool do? +

Create a new window in an existing tmux session. It is categorised as a Execute tool in the Tmux MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on tmux_create_window? +

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

What risk level is tmux_create_window? +

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

Can I rate-limit tmux_create_window? +

Yes. Add a rate_limit block to the tmux_create_window 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 tmux_create_window completely? +

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

tmux_create_window is provided by the Tmux MCP server (wenlixiao-cs/tmux-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.