start_message_timer · Tmux MCP Server MCP: Risk & Policy

WHAT IT DOES

What start_message_timer does on Tmux MCP Server

AI agents invoke start_message_timer 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 start_message_timer needs a policy

This tool executes automated, repeated commands to a tmux session based on configurable parameters (message content, timing, target session). While the message itself may be benign, the tool enables triggering arbitrary sequences of commands in active terminal sessions, which qualifies as Execute rather than Write. The automation aspect and external process control elevate it beyond simple data modification.

From the tool's definition Tool enables 'repeatedly send a message to a tmux session' which triggers automated actions on external processes.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

start_message_timer Rate-limited

start_message_timer 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": {
    "start_message_timer": {
      "limits": [
        {
          "counter": "start_message_timer_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 start_message_timer

What does the start_message_timer tool do? +

Start a timer to repeatedly send a message to a tmux session. 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 start_message_timer? +

Register the Tmux MCP Server MCP server in PolicyLayer and add a rule for start_message_timer: 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 start_message_timer? +

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

Can I rate-limit start_message_timer? +

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

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

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