Cmux Agent

CMUX MCP Server — a programmable terminal control plane for multi-agent AI workflows.

Turns CMUX into a remote-controllable terminal multiplexer that any AI coding CLI can be orchestrated through. One orchestrator agent spawns, monitors, and communicates with any number of AI agents running in parallel across multiple projects.

What This Does

• Spawn AI agents in CMUX workspaces — Claude Code, Gemini CLI, Codex CLI, OpenCode, Goose
• Inject prompts into running agent sessions as if a human typed them
• Read output from any pane — passive (fast) or deep (asks agents for status)
• Orchestrate — send different plans to different agents in one call
• Manage workspaces — create, rename, reorder, move between windows
• Split panes — horizontal, vertical, grid layouts, drag-to-split
• Browser automation — open URLs, navigate, snapshot DOM, evaluate JS, click/fill/type
• Sidebar metadata — status pills, progress bars, log entries
• Notifications — send alerts with blue ring indicators
• Session recovery — save/restore full layouts including CLI session IDs and conversations
• Auto-skip permissions — each CLI's autonomous mode is handled automatically
• Auto-save — sessions are saved automatically after every layout change

Architecture

+---------------------------------------------------+
|         Your AI Agent (Claude, etc.)               |
|                                                    |
|  "Launch 4 agents and distribute tasks"            |
|                       |                            |
|                  MCP Tool Calls                    |
|                       |                            |
+---------------------------------------------------+
|                  cmux-agent-mcp                        |
|              (this MCP server)                     |
|                       |                            |
|              cmux CLI commands                     |
|                       |                            |
+---------------------------------------------------+
|                     CMUX                           |
|                                                    |
|  +-- Sidebar ----+  +-- Tab Bar ---------------+  |
|  | agents        |  | Claude 1 x | ~/p/sensei  |  |
|  | > project-a   |  +-----------------------------+|
|  |   project-b   |  | +--------+ +--------+    |  |
|  |   outputs     |  | | Claude | | Gemini |    |  |
|  |   edit        |  | | Agent  | | Agent  |    |  |
|  +---------------+  | +--------+ +--------+    |  |
|                      | | Codex  | | Shell  |    |  |
|                      | | Agent  | |        |    |  |
|                      | +--------+ +--------+    |  |
|                      +-----------------------------+
+---------------------------------------------------+

Quick Start

Prerequisites

• Node.js (v22.5+)
• CMUX — install via brew tap manaflow-ai/cmux && brew install --cask cmux

Install

One command:

npm install -g cmux-agent-mcp

Install automatically registers the MCP server globally for all AI coding tools:

Config file	For
~/.claude.json	Claude Code, Codex
~/.cursor/mcp.json	Cursor
VS Code mcp.json	VS Code
~/.gemini/settings.json	Gemini CLI
~/.config/opencode/...	OpenCode

One install, every project, every tool. Existing config files are merged — other MCP servers won't be touched.

To re-run manually or for per-project setup:

cmux-agent-mcp init              # re-run global setup
cmux-agent-mcp init --project    # per-project setup (current dir)
cmux-agent-mcp init --root /path # per-project setup (specific dir)

Install from source

git clone https://github.com/multiagentcognition/cmux-agent-mcp.git
cd cmux-agent-mcp
npm install --ignore-scripts
npm run build
node build/cli.js init       # register globally

81 MCP Tools

Status & Discovery

Tool	Description
cmux_status	Check if CMUX is installed/running, show hierarchy summary
cmux_tree	Full hierarchy tree of windows, workspaces, panes, surfaces
cmux_identify	Context info for focused window/workspace/pane/surface
cmux_find	Search across windows and panes by content or title
cmux_start	Launch CMUX if not running
cmux_screenshot	Capture screenshot of CMUX window

Workspace Management

Tool	Description
cmux_list_workspaces	List all open workspaces
cmux_current_workspace	Get the currently active workspace
cmux_new_workspace	Create a new workspace with optional cwd/command
cmux_select_workspace	Switch to a specific workspace
cmux_close_workspace	Close a workspace and all its panes
cmux_rename_workspace	Rename a workspace (changes the sidebar name)
cmux_reorder_workspace	Reorder a workspace in the sidebar
cmux_move_workspace_to_window	Move a workspace to a different window

Window Management

Tool	Description
cmux_list_windows	List all open windows
cmux_current_window	Get the currently focused window
cmux_new_window	Create a new window
cmux_focus_window	Focus a specific window
cmux_close_window	Close a window
cmux_rename_window	Rename a window (changes the title bar)

Surface (Tab) Management

Tool	Description
cmux_new_surface	Create a new tab (terminal or browser)
cmux_close_surface	Close a tab
cmux_rename_tab	Rename a tab (changes the tab bar name)
cmux_move_surface	Move a tab to a different pane/workspace/window
cmux_reorder_surface	Reorder a tab within its pane
cmux_drag_surface_to_split	Turn a tab into its own split pane

Pane / Split Operations

Tool	Description
cmux_list_panes	List all panes in a workspace
cmux_list_pane_surfaces	List pane surfaces with refs
cmux_list_panels	List all panels in a workspace
cmux_new_split	Split a pane (left/right/up/down)
cmux_new_pane	Create a new pane
cmux_focus_pane	Focus a specific pane
cmux_resize_pane	Resize a pane
cmux_swap_pane	Swap two panes
cmux_break_pane	Move a pane to its own workspace
cmux_join_pane	Merge a pane into another
cmux_respawn_pane	Restart a pane's process

Text I/O

Tool	Description
cmux_send	Send text without pressing Enter
cmux_send_submit	Send text and press Enter
cmux_send_key	Send a key press (enter, ctrl+c, escape, etc.)
cmux_send_panel	Send text to a specific panel
cmux_read_screen	Read terminal output from a surface
cmux_capture_pane	tmux-compatible capture

Bulk Text Operations

Tool	Description
cmux_broadcast	Send same text + Enter to ALL panes
cmux_send_each	Send DIFFERENT text to each pane (in order)
cmux_send_submit_some	Send text to SPECIFIC surfaces only
cmux_send_key_all	Send a key to ALL panes (e.g., ctrl+c to cancel all)
cmux_read_all	Read output from all panes
cmux_read_all_deep	Deep read — prompts idle agents for status
cmux_workspace_snapshot	Full snapshot: tree + all output + sidebar state

Sidebar Metadata

Tool	Description
cmux_set_status	Set a sidebar status pill (key-value badge)
cmux_clear_status	Clear a status pill
cmux_list_status	List all status entries
cmux_set_progress	Set a progress indicator (0.0-1.0)
cmux_clear_progress	Clear the progress indicator
cmux_log	Write a log entry to the sidebar
cmux_sidebar_state	Get full sidebar state

Notifications

Tool	Description
cmux_notify	Send a notification (blue ring + sidebar highlight)
cmux_list_notifications	List all notifications
cmux_clear_notifications	Clear all notifications

Browser Automation

Tool	Description
cmux_browser_open	Open a browser surface
cmux_browser_navigate	Navigate: goto, back, forward, reload
cmux_browser_snapshot	DOM accessibility snapshot
cmux_browser_screenshot	Take a page screenshot
cmux_browser_eval	Execute JavaScript
cmux_browser_click	Click an element
cmux_browser_fill	Fill an input field
cmux_browser_type	Type text into an element
cmux_browser_wait	Wait for a condition (selector, text, URL, load state)
cmux_browser_get	Get page data (url, title, text, html, value, attr, count)
cmux_browser_tab	Manage browser tabs (new, list, switch, close)
cmux_browser_console	Get/clear console logs and errors

High-Level Launchers

Tool	Description
cmux_open_cli	Open a single AI CLI in a new or existing workspace
cmux_launch_agents	Create workspace with N agents in a grid layout
cmux_launch_grid	Create an exact rows x cols grid of panes
cmux_launch_mixed	Launch different CLIs in one workspace
cmux_orchestrate	Send different prompts to specific surfaces in one call
cmux_close_all	Close all workspaces

Session Management

Tool	Description
cmux_session_save	Save current state for crash recovery
cmux_session_recover	Recreate layout and resume CLI conversations
cmux_session_reconcile	Compare manifest vs live state, report drift

Orchestration Workflow

The typical multi-agent workflow:

1. cmux_launch_agents(cli: "claude", count: 4)
   → Creates a workspace with 4 Claude Code agents in a 2x2 grid

2. cmux_orchestrate(assignments: [
     { surface: "surface:10", text: "Implement the auth module..." },
     { surface: "surface:11", text: "Write tests for the API..." },
     { surface: "surface:12", text: "Refactor the database layer..." },
     { surface: "surface:13", text: "Update the documentation..." },
   ])
   → Each agent receives its specific task

3. cmux_read_all()
   → Check all agents' progress at once

4. cmux_read_all_deep()
   → Ask idle agents to summarize their status

Mixed-CLI orchestration:

cmux_launch_mixed(agents: [
  { cli: "claude", label: "Architect" },
  { cli: "gemini", label: "Reviewer" },
  { cli: "codex",  label: "Implementer" },
])

Session Recovery

Sessions are auto-saved after every layout change. If CMUX crashes or you restart your machine, call cmux_session_recover to recreate everything — including resuming CLI conversations.

CLI Session Resume

CLI	Resume Method
Claude Code	--resume <session-id> or --continue
Gemini CLI	--resume latest
Codex	codex resume <session-id>
OpenCode	--session <session-id> or --continue
Goose	session --resume --session-id <session-id>

Session IDs are detected from each CLI's session storage:

• Claude: ~/.claude/sessions/*.json
• Codex: ~/.codex/sessions/**/rollout-*.jsonl
• Gemini: ~/.gemini/projects.json + ~/.gemini/tmp/*/chats/*.json
• OpenCode: ~/.local/share/opencode/opencode.db (SQLite)
• Goose: goose session list --format json

Auto-Trust & Permissions

When launching agents, cmux-agent-mcp automatically:

• Claude Code: Sets hasTrustDialogAccepted: true in ~/.claude.json
• Gemini CLI: Adds directory to ~/.gemini/trustedFolders.json
• Codex: Adds trust_level = "trusted" to ~/.codex/config.toml
• OpenCode: Sets permission: 'allow' in its config

No permission prompts — agents start working immediately.

ID Reference Format

CMUX uses ref format for IDs: workspace:5, surface:8, pane:3, tab:2, window:1. Always use the ref format, not bare numbers. Use cmux_identify or cmux_list_pane_surfaces to discover refs.

CMUX Hierarchy

Window → Workspace(s) → Pane(s) → Surface(s) → Panel(s)

• Window: macOS window
• Workspace: Sidebar entry (like a "tab group")
• Pane: Split region within a workspace
• Surface: Tab within a pane (terminal or browser)
• Panel: Content inside a surface

Naming Conventions

What you see	What to rename
Sidebar entry	cmux_rename_workspace
Tab at top	cmux_rename_tab
Window title bar	cmux_rename_window

Platform Support

macOS only — CMUX is a native macOS application.

Testing

The test/full-test-suite.md file contains a comprehensive test plan covering all 81 tools. Give it to any AI coding agent to execute:

Tag test/full-test-suite.md and say "Execute this test suite"

Tests leave all workspaces open for human visual verification before cleanup.

License

PolyForm Strict 1.0.0