MCP Tic-Tac-Toe

A Model Context Protocol (MCP) server that enables AI assistants to play tic-tac-toe through standardized tool interfaces. Perfect for demonstrating AI-human collaboration and MCP integration.

Overview

This project implements a complete tic-tac-toe game as an MCP server, allowing AI assistants like Claude to:

• Create and manage multiple game sessions
• Make strategic moves and analyze positions
• Provide game commentary and suggestions
• Play against humans or other AIs

Quick Start

Prerequisites

• Go 1.19+ installed
• Claude Code or other MCP-compatible client

Installation

git clone https://github.com/tomholford/mcp-tic-tac-toe
cd mcp-tic-tac-toe
go mod tidy
go build -o bin/server cmd/server.go

Basic Usage

# Start MCP server (stdio transport)
./bin/server

# Or specify transport method
./bin/server -transport=sse -addr=:8080

MCP Configuration

Claude Code Setup

1. Build the server:

   go build -o bin/server cmd/server.go
   

2. Add to your MCP configuration:

   Create or edit your MCP configuration file:

   # For macOS/Linux
   ~/.config/claude-code/mcp_servers.json
   
   # For Windows  
   %APPDATA%\\claude-code\\mcp_servers.json
   

3. Add the server configuration:

   {
     "mcpServers": {
       "tic-tac-toe": {
         "command": "/full/path/to/mcp-tic-tac-toe/bin/server",
         "args": ["-transport=stdio"],
         "env": {}
       }
     }
   }
   

4. Restart Claude Code and the tic-tac-toe tools will be available. c

Claude Desktop

"tic-tac-toe": {
  "command": "/full/path/to/mcp-tic-tac-toe/bin/server",
  "args": [""]
}

Available MCP Tools

The server exposes 8 tools for complete game management:

Game Management

• new_game - Create a new tic-tac-toe game

  • Optional: game_id (string) - Custom game identifier
  • Returns: Game ID, starting player, initial board

• list_games - Show all active game sessions

  • Returns: List of active game IDs

• reset_game - Reset a game to initial state

  • Required: game_id (string)
  • Returns: Confirmation and fresh board

Gameplay

• make_move - Execute a move on the board

  • Required: game_id (string), position (A1-C3), player (X/O)
  • Returns: Updated board, game status, next player

• get_board - Get current board state

  • Required: game_id (string)
  • Returns: Board display, current player, move count

• get_available_moves - List all valid moves

  • Required: game_id (string)
  • Returns: Available positions for current player

Analysis

• get_status - Check game status and winner

  • Required: game_id (string)
  • Returns: Game status (ongoing/won/draw), winner if applicable

• analyze_position - Get strategic analysis

  • Required: game_id (string)
  • Returns: Position analysis and board state

Usage Examples

Start a New Game

AI: Use the new_game tool
→ New game created with ID: game-a1b2c3d4
  Starting player: X
  Initial board:
    A B C
  1 · · ·
  2 · · ·  
  3 · · ·

Make Strategic Moves

Human: I'll take the center
AI: Use make_move tool with {"game_id": "game-a1b2c3d4", "position": "B2", "player": "X"}

AI: Let me analyze the position first
AI: Use analyze_position tool → Shows current state and opportunities

AI: I'll take a corner for strategic advantage  
AI: Use make_move tool with {"game_id": "game-a1b2c3d4", "position": "A1", "player": "O"}

Get Game Status

AI: Use get_status tool → Game Status: Ongoing, Current player: X, Move count: 2
AI: Use get_available_moves tool → Available moves (7): A2, A3, B1, B3, C1, C2, C3

Transport Options

The server supports three transport methods:

1. Stdio (Default)

Best for local MCP clients like Claude Code:

./bin/server -transport=stdio

2. Server-Sent Events (SSE)

For web applications and real-time updates:

./bin/server -transport=sse -addr=:8080

3. Streamable HTTP

For traditional HTTP integrations:

./bin/server -transport=http -addr=:8080

Development

Project Structure

mcp-tic-tac-toe/
├── cmd/
│   ├── server.go          # MCP server main entry point
│   └── demo.go            # Game logic demonstration  
├── game/                  # Core tic-tac-toe logic
│   ├── types.go           # Game data structures
│   ├── engine.go          # Game rules and validation
│   └── engine_test.go     # Game logic tests
├── server/                # MCP server implementation  
│   ├── server.go          # MCP server setup and tools
│   ├── handlers.go        # Tool request handlers
│   └── server_test.go     # MCP integration tests
└── bin/                   # Built executables

Running Tests

# Test all packages
go test ./game ./server -v

# Test specific functionality
go test ./game -run TestWinConditions
go test ./server -run TestMakeMoveTool

Building from Source

# Build server
go build -o bin/server cmd/server.go

# Build demo
go build -o bin/demo cmd/demo.go

# Run demo (no MCP required)
./bin/demo

Resources

• MCP Specification - Official MCP documentation
• mcp-go Library - Go MCP implementation used in this project