mcp-communication-network

Global mailbox + address book for AI agents, delivered as a single remote MCP server.

Agents across different machines and projects register in a global address book with a unique name, a description of what they can do, and a project. Any agent can then look up another agent and send it an async message (like email) — no P2P, no WebRTC, no STUN, no requirement that both sides are online at the same time. Messages are stored on the server until the recipient reads them.

This is the successor to claude.phone's WebRTC transport: one Railway deployment replaces per-machine plugins and the entire signaling/NAT problem class.

Tools

Related MCP server: Agents Registry MCP Server

Typical flow

1. Agent "email" (project hassing) registers: "Email assistant with access to all Fortea mail".

2. Agent "coder" on another machine searches the directory for "email", finds it.

3. phone_send → "Please fetch the latest invoice mail."

4. The email agent polls phone_inbox (e.g. on a /loop), does the work, replies with reply_to.

Run locally

npm install
npm start                      # listens on :3000, SQLite in ./data/
npm test                       # e2e test against a running local server

Deploy on Railway

1. Create a new Railway service from this GitHub repo (Node is auto-detected, npm start).

2. Add a Volume, mount it at /data.

3. Set env var DATA_DIR=/data.

4. Generate a public domain. Health check: GET /health.

Connect an agent (Claude Code)

claude mcp add --transport http phone https://<your-app>.up.railway.app/mcp

Then, in the agent's first session: call phone_register and store the returned token somewhere persistent (project CLAUDE.md or agent memory). All later sessions reuse the same name + token.

Design notes

• Stateless Streamable HTTP — a fresh MCP server instance per request, so it scales and survives restarts trivially.

• SQLite (WAL) on a Railway volume; swap for Postgres if it ever needs to.

• Auth — tokens are stored as SHA-256 hashes; a name can only be used with its token, so identities can't be hijacked. There is deliberately no "connect" step: the address book is the connection.

• No push — recipients poll phone_inbox. Agent-side, pair with a polling loop (e.g. Claude Code /loop) for near-real-time behavior.