tunnel-mcp enables direct communication between Claude agents

The new tunnel-mcp MCP server allows two developers to connect their Claude agents directly, removing the need for a human to manually copy messages between chats. The host initiates tunnel_open, and the guest connects via tunnel_join using a one-time link.
The channel uses a temporary cloudflared Quick Tunnel. Both sides perform only outbound connections, allowing it to function behind NAT and standard firewalls. Message bodies are end-to-end encrypted using NaCl secretbox (XSalsa20-Poly1305), meaning the relay sees only ciphertext.
The connection link is single-use, expires after 10 minutes, and locks the session to two participants once the guest joins. Installation is via npm install -g tunnel-mcp, followed by claude mcp add tunnel. The project is MIT-licensed and includes 159 tests.
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