cmux_capture_pane

THE RISK

Low Risk

Why cmux_capture_pane needs a policy

This tool reads and retrieves the current output/content of a terminal pane. It performs a read-only capture operation with no side effects on the session or its state.

From the tool's definition Capture pane output (tmux-compatible)

Documented attack patterns abuse exactly the kind of access cmux_capture_pane gives an agent:

POLICY

How to control cmux_capture_pane

PolicyLayer is an MCP gateway — it sits between your AI agents and Cmux Agent, and nothing reaches the server without passing your rules. This is the rule we recommend for cmux_capture_pane:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "cmux_capture_pane": {}
  }
}

cmux_capture_pane is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Cmux Agent — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

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EXPLORE

Related tools and policies

More Cmux Agent tools

Destructive cmux_clear_notifications Clear all notifications. Destructive cmux_close_all Close ALL workspaces (or all except specific ones). Use Destructive cmux_close_surface Close a surface (tab). Destructive cmux_close_window Close a window. Destructive cmux_close_workspace Close one or more workspaces and all their panes. Pass a single ref or an array of refs. Execute cmux_browser_console Get or clear browser console logs/errors. Execute cmux_batch Execute multiple CMUX operations in a single MCP call. Each step references an existing cm Execute cmux_browser_eval Execute JavaScript in the browser page.

All 63 Cmux Agent tools →

Read tools on other servers

M-Team MCP Server get_torrent_detail YouTube MCP Server search_channel Android Forensics ADB MCP Server parse_browser_history 0xarchive web3_challenge

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about cmux_capture_pane

What does the cmux_capture_pane tool do? +

Capture pane output (tmux-compatible). Works on all surface types. It is categorised as a Read tool in the Cmux Agent MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on cmux_capture_pane? +

Register the Cmux Agent MCP server in PolicyLayer and add a rule for cmux_capture_pane: 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 Cmux Agent. Nothing to install.

What risk level is cmux_capture_pane? +

cmux_capture_pane is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit cmux_capture_pane? +

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

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

cmux_capture_pane is provided by the Cmux Agent MCP server (multiagentcognition/cmux-agent-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Cmux Agent tool call.

Start from Cmux Agent, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →