How do I use MCP-to-MCP Tic-Tac-Toe?

1. Click on "Install Server". 2. Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state. 3. In the chat, type @ followed by the MCP server name and your instructions, e.g., "@MCP-to-MCP Tic-Tac-Toe use make_move to play tic-tac-toe" That's it! The server will respond to your query, and you can continue using it as needed. Here is a step-by-step guide with screenshots.

MCP-to-MCP Communication

Two LLMs play Tic-Tac-Toe against each other through a single MCP tool make_move. No human input, AIs autonomously take turns via ping-pong SSE relay.

Play

Local (Claude Code, Codex) Or Remote

# (starts local server, hosts on :8787 via stdio, connects or auto-joins) and ask: `use make_move to play tic-tac-toe`
claude mcp add tictactoe -- npx -y github:PsychoSmiley/mcp-to-mcp

# Or using Cloudflare MCP Remote
claude mcp add tictactoe --transport http https://mcp-tictactoe.edge-relay-9x.workers.dev/mcp

Or simply from claude.ai web in Settings -> Connectors URL: https://mcp-tictactoe.edge-relay-9x.workers.dev/mcp

# Optionally, to self-host on Cloudflare Workers (free)
Set CLOUDFLARE_API_TOKEN=your-token-here && Set CLOUDFLARE_ACCOUNT_ID=your-account-id && git clone https://github.com/PsychoSmiley/mcp-to-mcp && cd mcp-to-mcp && npm install && npx wrangler deploy # Auto-deploys on push via GitHub Actions (add secrets in repo Settings -> Secrets).

Then open two separate Claude chats. In each ask: use make_move to play tic-tac-toe

How it works

make_move(move) places your mark, hangs (SSE stream open) until the opponent moves, returns their move. No database - game state lives in RAM.

                              -> time ->
Agent A: <mcp make_move("B2")>{LLM think}<mcp make_move("C3")>{LLM think}<mcp make_move("B1")>
Agent B:            <mcp make_move("A1")>{LLM think}<mcp make_move("C1")>{LLM think}
                                                                   -> "Game over - X wins!"

server.js  - Game logic + local Node.js server (stdio + HTTP)
worker.js  - Cloudflare Worker + Durable Object (imports game logic from server.js)

Remote uses a single Durable Object that routes all players to the same game room. Polling via setTimeout yields to the event loop - when one player moves, the other's poll picks it up.