MCP server agent-intercom

Let Claude Code, Codex CLI and Antigravity (Gemini) message each other, and land each message straight in the other agent's open session.

If it saves you time, a ⭐ helps other people find it.

Get started · See it work · How push works · Across machines · CLI · Security · Contributing

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Get started

npx agent-intercom install

Using Claude Code only? Install it as a plugin instead:

/plugin install agent-intercom --marketplace iambashar/agent-intercom

On Claude Code older than 2.1.275: /plugin marketplace add iambashar/agent-intercom, then /plugin install agent-intercom@agent-intercom. The plugin also adds a skill that teaches Claude the mailbox conventions.

The npx command registers the MCP server with every CLI it finds. Restart them, and each agent gets three tools: mail_send, mail_check and mail_peers. Then ask in plain words:

You → Claude: Ask codex to review the diff in src/parser.ts and wait for its answer.

Turn on live push so nobody has to poll. Install it globally, because the daemon needs a stable path:

npm i -g agent-intercom
agent-intercom install --push

CLI	Registration	Extra for push
Claude Code	claude mcp add, user scope	nothing; uses Claude Code's peer socket
Codex CLI	a managed block in ~/.codex/config.toml (backed up first)	nothing; uses the Codex app-server daemon
Antigravity (agy)	agy mcp add	a session hook in ~/.gemini/config/hooks.json

Use --only claude|codex|gemini for one CLI, and --local to pin a git checkout instead of npx. agent-intercom uninstall removes all of it, including the push daemon.

[!NOTE] The old gemini CLI no longer accepts personal Google AI Pro sign-ins; Google moved those users to the Antigravity CLI (agy). Its agent is named gemini here by default.

See it work

Neither agent polls. The request appears in Codex as a new turn the moment it is sent, and the reply lands in Claude the same way.

What you get

Supported agents

Agent	Mailbox name	How a message reaches the open session
	claude	Claude Code's local peer-messaging socket, the channel SendMessage uses between sessions. Arrives labelled as from another session.
	codex	The shared app-server daemon the Codex TUI runs on: turn/start, or turn/steer when a turn is already running.
	gemini	agy agentapi send-message into the conversation. Each session registers itself once through a hook.
Any other MCP client	anything	No push. It reads with mail_check, or blocks with mail_check(wait_seconds=300).

Tool	What it does
mail_send(to, body, reply_to?)	Drop a message in another agent's inbox
mail_check(wait_seconds?)	Read and consume your messages; with wait_seconds (max 300) it blocks until one arrives
mail_peers()	List known agents

How push works

sequenceDiagram
    autonumber
    participant C as Claude Code
    participant M as ~/.agent-mail/codex/inbox
    participant P as pushd
    participant X as Codex CLI (open session)
    C->>M: mail_send(to: "codex", body)
    M-->>P: file appears (fs.watch, no polling)
    P->>M: claim: rename to <id>.json.pushing
    P->>X: turn/start with the message
    X-->>P: turn accepted
    P->>M: move to read/
    Note over X: Codex works on it, then replies with mail_send(to: "claude")

• Delivered once. The daemon renames a message before pushing it, and mail_check renames before reading. Whoever wins the rename delivers it.

• Fails safe. A failed push puts the file back in the inbox and retries after 30 s. If no session is open, the message waits for mail_check.

• Addressing. Pick a session with claude.<session-name>, codex.<thread-id-prefix> or gemini.<conversation-prefix>. Otherwise the most recently active session gets it, or the one named in ~/.agent-mail/routes.json:

  { "claude": "api-server", "codex": "019f018a" }
  

[!WARNING] Push relies on undocumented internals of all three CLIs, and an update can change them without notice. When that happens, pushes fail, get logged, and the mail falls back to the inbox. Protocol details: docs/live-push.md.

• Claude Code: docs/claude-monitor.md. agent-intercom watch claude under the Monitor tool wakes the session when mail arrives.
• Codex: docs/codex-listen.md. A listener prompt that loops on mail_check(wait_seconds=300).

Across machines

Agents on a machine with no shared filesystem, such as a GPU server or an HPC cluster, join over SSH with bridge.sh. It moves each message to the machine its recipient lives on, and pulled mail is pushed like any other.

BRIDGE_HOST=gpu-box REMOTE_AGENTS="claude-gpu" ./bridge.sh

flowchart LR
    subgraph laptop["💻 Laptop"]
        A[claude] & B[codex] & G[gemini]
    end
    subgraph gpu["🖥️ gpu-box"]
        R[claude-gpu]
    end
    laptop <-- "bridge.sh · rsync over SSH" --> gpu

More: docs/remote-bridge.md.

More than one session per CLI

Names are just AGENT_NAME. Give each session its own, for example claude-api and claude-web:

npx agent-intercom install --only claude --claude-name claude-api

CLI

agent-intercom install [--only claude|codex|gemini] [--claude-name N] [--codex-name N] [--gemini-name N] [--local] [--push]
agent-intercom uninstall        MCP entries, agy hook and push daemon
agent-intercom push install     push daemon as a login service (launchd / systemd --user)
agent-intercom push uninstall
agent-intercom push run         push daemon in the foreground
agent-intercom status           unread/read counts per agent
agent-intercom watch <name>     one line per new message, without consuming it
agent-intercom serve            the MCP server on stdio

Security

This is a local mailbox with no authentication. Any process running as you can write to ~/.agent-mail/*/inbox, and an agent treats a message as input to act on. With push on, that input reaches your open sessions without you typing anything.

• Treat inbox contents as untrusted text. Don't let one agent approve destructive actions because a message told it to.
• Pushed messages are labelled [agent-intercom] message <id> from <sender>. Claude Code also marks them as from another session, not from you.
• Push reads tokens only your user can read (~/.claude/sessions/*.key, the agy session token) and talks only to local sockets. Nothing leaves the machine.

See SECURITY.md to report a problem. Set AGENT_MAIL_DIR to move the mailbox, for example into a project folder.

🤝 Contributing

Contributions are welcome, from a typo fix to support for a new agent.

I want to…	Start here
Fix something small	Good first issues
Support another coding agent	docs/adding-an-agent.md
Report a push that broke after a CLI update	Bug report
Ask a question or pitch an idea	Discussions

Read CONTRIBUTING.md before opening a pull request. Everyone here follows the code of conduct.

Develop

git clone https://github.com/iambashar/agent-intercom && cd agent-intercom
npm test                          # node --test, no dependencies
python3 scripts/build-assets.py   # rebuild the README artwork

Zero runtime dependencies; Node 20+. See CONTRIBUTING.md and the changelog.

MIT licensed · made for people who run more than one coding agent

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