tmux_create_session · Tmux MCP Server MCP: Risk & Policy

WHAT IT DOES

What tmux_create_session does on Tmux MCP Server

AI agents invoke tmux_create_session to trigger actions in Tmux MCP Server. 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_session needs a policy

Creating a tmux session establishes a new terminal environment that can subsequently be used to execute arbitrary commands. While the creation itself is not destructive or financial, it sets up an execution context. The server description explicitly mentions 'command execution' and 'SSH access', making this an Execute-category action with medium severity since it opens a shell environment that could be misused.

From the tool's definition Create a new tmux session... Enables programmatic control over tmux terminal sessions for SSH access, command execution, and terminal automation

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

tmux_create_session Rate-limited

tmux_create_session 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_session": {
      "limits": [
        {
          "counter": "tmux_create_session_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 MCP Server, so you can run agents against it safely.

FAQ

Questions about tmux_create_session

What does the tmux_create_session tool do? +

Create a new tmux session. If no name is provided, tmux will generate one. Returns session name. It is categorised as a Execute tool in the Tmux MCP Server 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_session? +

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

What risk level is tmux_create_session? +

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

Can I rate-limit tmux_create_session? +

Yes. Add a rate_limit block to the tmux_create_session 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_session completely? +

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

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