MCP channel

A lightweight MCP channel server that lets agentic agents discover and communicate with each other through direct messages and named channels. Built for multi-agent orchestration.

Architecture

┌─────────────┐     HTTP/SSE     ┌────────────┐     HTTP/SSE     ┌─────────────┐
│    Agent    │◄────────────────►│   Broker   │◄────────────────►│    Agent    │
│  Session A  │  (channel.ts)    │ (broket.ts)│  (channel.ts)    │  Session B  │
└─────────────┘                  └────────────┘                  └─────────────┘

Each agent session spawns its own channel.ts MCP server as a subprocess. These servers connect to a shared broker.ts HTTP server that routes messages between them.

Quick Start

1. Install dependencies

bun install

2. Start the broker

The broker must be running before any agent sessions connect:

bun run broker.ts

By default it listens on port 8900. Override with CHANNEL_BROKER_PORT=9000 bun run broker.ts.

3. Start agent sessions

In separate terminals, start agent sessions with different names. For Claude Code:

# Terminal 1
CHANNEL_SESSION_NAME=frontend claude --dangerously-load-development-channels server:channel

# Terminal 2
CHANNEL_SESSION_NAME=backend claude --dangerously-load-development-channels server:channel

# Terminal 3
CHANNEL_SESSION_NAME=coordinator claude --dangerously-load-development-channels server:channel

Each session auto-registers with the broker and can immediately communicate.

Tools Available to the agent

| Tool | Description | |------|-------------| | send_message | Send a direct message to a session (by name) or to a channel | | list_sessions | List all registered sessions and their online status | | list_channels | List available channels and their members | | create_channel | Create a named channel for group communication | | join_channel | Join an existing channel | | leave_channel | Leave a channel |

Usage Examples

Direct messaging

Tell one agent session:

"Send a message to the backend session asking it to create the API endpoint for /users"

Channel-based coordination

Tell the coordinator session:

"Create a channel called 'project' and invite the other sessions to coordinate on building the user dashboard"

Multi-agent workflow

1. Start a "coordinator" session and tell it the overall plan
2. Start "frontend" and "backend" sessions
3. The coordinator creates a channel, and instructs each agent on their role
4. Agents communicate through the channel to coordinate their work

Configuration

| Environment Variable | Default | Description | |---------------------|---------|-------------| | CHANNEL_SESSION_NAME | session-<random> | Human-readable name for this session | | CHANNEL_BROKER_URL | http://127.0.0.1:8900 | Broker server URL | | CHANNEL_BROKER_PORT | 8900 | Port for the broker (broker.ts only) |

How It Works

1. Broker (broker.ts): A lightweight HTTP server that maintains a registry of sessions, manages named channels, and routes messages via SSE streams
2. Channel MCP Server (channel.ts): An MCP server that agent spawns as a subprocess. It registers with the broker, opens an SSE connection for inbound messages, and exposes tools for sending messages
3. Message delivery: When the agent calls send_message, the MCP server POSTs to the broker, which pushes the message via SSE to the recipient's MCP server, which delivers it to the recipient's agent session as a <channel> notification