send_command · TmuxControlLib MCP Server MCP: Risk & Policy

WHAT IT DOES

What send_command does on TmuxControlLib MCP Server

AI agents invoke send_command to trigger actions in TmuxControlLib 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 send_command needs a policy

This tool executes arbitrary shell commands in a running terminal session. An AI agent could use it to run any command on the host system, including destructive or malicious operations. The blast radius is critical since there are no apparent restrictions on what commands can be sent.

From the tool's definition 'Send a command to a pane' — sends arbitrary commands to a live terminal pane in a tmux session

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

send_command Rate-limited

send_command 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": {
    "send_command": {
      "limits": [
        {
          "counter": "send_command_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 TmuxControlLib MCP Server, so you can run agents against it safely.

FAQ

Questions about send_command

What does the send_command tool do? +

Send a command to a pane. It is categorised as a Execute tool in the TmuxControlLib 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 send_command? +

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

What risk level is send_command? +

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

Can I rate-limit send_command? +

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

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

send_command is provided by the TmuxControlLib MCP Server MCP server (jbwinters/tmuxcontrollib). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.