Claude Intercom

Real-time messaging between Claude Code instances. When one agent sends a message, the others get it instantly — no polling, no manual checks.

Built as an MCP server + filesystem watcher that wakes idle agents automatically via asyncRewake.

How it works

Terminal 1                          Terminal 2
┌─────────────────────┐            ┌─────────────────────┐
│ claude (agent sgup)  │            │ claude (agent 4jov)  │
│                      │            │                      │
│ > send("4jov",       │ ──JSON──▶ │ 📬 sgup: tu touches  │
│   "tu touches        │   file    │    auth.ts ?          │
│    auth.ts ?")       │            │                      │
│                      │ ◀──JSON── │ > reply("Non,        │
│ 📬 4jov: Non,        │   file    │   je suis sur        │
│   je suis sur billing│            │   billing")          │
└─────────────────────┘            └─────────────────────┘

• Each instance gets a unique 4-char code (e.g. x7k2) on startup
• Messages are JSON files in a shared store/ directory
• A fs.watch watcher detects new files instantly and wakes the receiving agent
• Dead agents are auto-cleaned via PID checking

Install

# Clone
git clone https://github.com/sanztheo/claude-intercom.git ~/.claude/mcp-intercom

# Install deps
cd ~/.claude/mcp-intercom && bun install

1. Register the MCP server

Add to ~/.mcp.json:

{
  "mcpServers": {
    "intercom": {
      "type": "stdio",
      "command": "bun",
      "args": ["~/.claude/mcp-intercom/src/server.ts"]
    }
  }
}

2. Add the auto-notification hooks

Add to ~/.claude/settings.json under "hooks":

{
  "hooks": {
    "PreToolUse": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "bun ~/.claude/mcp-intercom/src/hook.ts",
            "timeout": 3000
          }
        ]
      }
    ],
    "Stop": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "bun ~/.claude/mcp-intercom/src/watcher.ts",
            "asyncRewake": true,
            "timeout": 300000
          }
        ]
      }
    ],
    "SessionStart": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "bun ~/.claude/mcp-intercom/src/watcher.ts",
            "asyncRewake": true,
            "timeout": 300000
          }
        ]
      }
    ]
  }
}

3. (Optional) Add the skill

Copy skill/SKILL.md to ~/.claude/skills/intercom/SKILL.md so agents proactively coordinate.

MCP Tools

Tool	Description
who	List active agents (filtered by project by default)
send	Send a message to an agent or broadcast to "all"
reply	Reply to a message (auto-acks the original)
peek	Check inbox for unread messages
ack	Acknowledge and delete a message
ack_all	Clear entire inbox

Auto-notification

Three layers ensure agents never miss a message:

Layer	When	How
Watcher (SessionStart + Stop)	Agent is idle	fs.watch on inbox dir → exit(2) → asyncRewake wakes the model
Hook (PreToolUse)	Agent is working	Checks inbox before every tool call
Skill (always active)	Agent makes decisions	Guides agent to announce work and check messages

Architecture

~/.claude/mcp-intercom/
├── src/
│   ├── server.ts    # MCP server — 6 tools, auto-generated agent codes
│   ├── store.ts     # Filesystem store — presence, messages, sessions
│   ├── hook.ts      # PreToolUse hook — checks inbox on every tool call
│   └── watcher.ts   # fs.watch — instant detection, asyncRewake push
├── skill/
│   └── SKILL.md     # Always-active skill for proactive coordination
└── store/           # Runtime data (gitignored)
    ├── presence/    # {code}.json — agent registration + PID
    ├── messages/    # {code}/*.json — per-agent inboxes
    └── sessions/    # {pid}.code — PID-to-agent-code mapping

Session linking (how the hook finds "its" agent)

The MCP server and hooks both run as children of the same Claude Code process. On startup, the server writes its agent code to sessions/{pid}.code for each PID in its ancestor chain. The hook walks up its own ancestor chain and matches against these files — the common ancestor (Claude Code) is the link.

Requirements

• Bun runtime
• Claude Code v2.1+
• macOS or Linux

License

MIT