game-mcp: Instructions file for GitHub Copilot

Game Discovery MCP Server - AI Agent Instructions

Architecture Overview

This is a Model Context Protocol (MCP) server built as a single C# script (game-mcp.cs) that discovers installed games across multiple Windows platforms. The project uses:

• Single-file architecture: Everything in game-mcp.cs (683 lines) - no traditional project structure
• Top-level program: Uses C# 9+ top-level statements with inline package references
• MCP framework: Uses [email protected] with .NET hosting
• JSON source generation: Uses GameJsonContext for AOT-compatible serialization

Key Patterns & Conventions

MCP Tool Registration Pattern

[McpServerToolType]
public static class GameDiscoveryTools
{
    [McpServerTool(Name = "discover_games")]
    [Description("...")]
    public static async Task<string> DiscoverGames() { ... }
}

Platform Discovery Pattern

Each platform (Steam, Epic, GOG, Xbox, Registry) follows this structure:

• Private DiscoverXxxGames() method returning List<Game>
• Registry/file system scanning with error isolation
• Graceful degradation when platforms unavailable
• Consistent Game object mapping

Error Handling Convention

• Continue on platform errors: Individual platform failures don't break discovery
• Stderr logging: Uses Console.Error.WriteLine() for debugging without breaking MCP protocol
• JSON error responses: All tools return JSON with ErrorResponse type for failures

JSON Serialization Approach

• Source generation required: Uses GameJsonContext.Default.XxxType pattern
• Response classes: Separate DTOs (GameInfo, GameDiscoveryResult, LaunchResponse, ErrorResponse)
• No reflection: AOT-compatible with [JsonSerializable] attributes

Critical Development Workflows

Running the MCP Server

dotnet run game-mcp.cs  # Starts stdio MCP server

VS Code Integration

Configure in .vscode/mcp.json:

{
  "servers": {
    "game-discovery": {
      "type": "stdio", 
      "command": "dotnet",
      "args": ["run", "D:\\Repos\\game-mcp\\game-mcp.cs"]
    }
  }
}