write_to_terminal · Iterm2 MCP: Risk & Policy

WHAT IT DOES

What write_to_terminal does on Iterm2

AI agents invoke write_to_terminal to trigger actions in Iterm2. 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 write_to_terminal needs a policy

Writing to a terminal on a system that provides full iTerm2 control almost certainly means sending keystrokes or commands to a terminal session, which constitutes arbitrary command execution. The blast radius is critical because any shell command can be executed, including destructive or data-exfiltrating ones.

From the tool's definition Tool name 'write_to_terminal' on a server described as providing 'full control over iTerm2 terminal sessions' that can 'run commands' and 'interact with terminal sessions'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

write_to_terminal Rate-limited

write_to_terminal 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": {
    "write_to_terminal": {
      "limits": [
        {
          "counter": "write_to_terminal_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 Iterm2, so you can run agents against it safely.

FAQ

Questions about write_to_terminal

What does the write_to_terminal tool do? +

write_to_terminal. It is categorised as a Execute tool in the Iterm2 MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on write_to_terminal? +

Register the Iterm2 MCP server in PolicyLayer and add a rule for write_to_terminal: 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 Iterm2. Nothing to install.

What risk level is write_to_terminal? +

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

Can I rate-limit write_to_terminal? +

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

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

write_to_terminal is provided by the Iterm2 MCP server (lorencarvalho/iterm2-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.