terminal-write · TermSSH MCP: Risk & Policy

WHAT IT DOES

What terminal-write does on TermSSH MCP

AI agents invoke terminal-write to trigger actions in TermSSH MCP. 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 terminal-write needs a policy

This tool sends arbitrary input to an interactive SSH terminal session, enabling execution of any shell command on a remote system, including destructive operations, privilege escalation via sudo, and system modifications. The blast radius is critical as it provides unrestricted remote code execution on the target system.

From the tool's definition 'Write input into an existing interactive terminal session. Use this for ordinary commands and sudo-interactive flows instead of exec tools.'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

terminal-write Rate-limited

terminal-write 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": {
    "terminal-write": {
      "limits": [
        {
          "counter": "terminal-write_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 TermSSH MCP, so you can run agents against it safely.

FAQ

Questions about terminal-write

What does the terminal-write tool do? +

Write input into an existing interactive terminal session. Use this for ordinary commands and sudo-interactive flows instead of exec tools. It is categorised as a Execute tool in the TermSSH MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on terminal-write? +

Register the TermSSH MCP server in PolicyLayer and add a rule for terminal-write: 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 TermSSH MCP. Nothing to install.

What risk level is terminal-write? +

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

Can I rate-limit terminal-write? +

Yes. Add a rate_limit block to the terminal-write 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 terminal-write completely? +

Set action: deny in the PolicyLayer policy for terminal-write. 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 terminal-write? +

terminal-write is provided by the TermSSH MCP server (rayss868/termssh-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.