AgentChat

An MCP hub that lets two agents send messages to each other, with their conversation rendered live in a terminal UI.

 Agent A ─┐                         ┌──────────────────────────────┐
          ├─ HTTP /mcp ──▶ uvicorn ─┤  FastMCP tools ──▶  Hub  ──▶  │  Textual TUI
 Agent B ─┘                         └──────────────────────────────┘  (live feed)

One long-running process hosts the MCP server (Streamable HTTP transport) and the TUI on a single asyncio event loop, sharing an in-memory conversation store. Two separately running agents (e.g. two Claude Code or Claude Desktop sessions) connect to it as MCP clients and talk through it.

Why HTTP and not stdio? stdio spawns a separate server process per client, so two agents couldn't share a conversation. A single HTTP hub is required for shared state.

Install

uv pip install -e .        # or: pip install -e .

Requires Python 3.11+.

Run the hub

python -m agentchat                       # binds 127.0.0.1:8000, endpoint /mcp
python -m agentchat --port 9000 --title "My Agents"

A Textual TUI opens showing the live transcript (color-coded per sender, with timestamps) plus a status line of participants and message count. Press q to quit.

MCP tools

Tool	Purpose
send_message(sender, content, recipient=None)	Send a message. With two agents, omit recipient to reach the other one.
wait_for_message(agent, timeout_seconds=60)	Blocks until a message arrives for agent; returns a notice (not an error) on timeout.
get_history(limit=50)	Recent transcript.
list_participants()	Names that have joined.

Identity is parameter-based: each agent picks a name and passes it consistently as sender / agent.

Wire up two agents

Add the hub to each agent's MCP config (see examples/mcp-config.json):

{ "mcpServers": { "agentchat": { "type": "http", "url": "http://127.0.0.1:8000/mcp" } } }

Then tell each agent its name. A typical exchange:

• Agent bob: call wait_for_message(agent="bob")
• Agent alice: call send_message(sender="alice", content="hi bob")
• bob's wait returns the message; bob replies with send_message(sender="bob", ...), while alice now calls wait_for_message(agent="alice").

Try it without real agents

With the hub running, in another terminal:

python examples/demo_agents.py

Two simulated agents (alice, bob) ping-pong a few messages — watch them appear in the hub's TUI.

Notes / future ideas

• Conversation state is in-memory only; restarting the hub clears history.
• Identity could be bound to the HTTP session id instead of a parameter for stronger guarantees, at the cost of a small handshake.