csharp-mcp-server-generator

Generate C# MCP Server

Create a complete Model Context Protocol (MCP) server in C# with the following specifications:

Requirements

1. Project Structure: Create a new C# console application with proper directory structure in a new empty subdirectory that the user confirms first; ask the user before replacing any existing files or projects
2. NuGet Packages: Include ModelContextProtocol (prerelease) and Microsoft.Extensions.Hosting
3. Logging Configuration: Configure all logs to stderr to avoid interfering with stdio transport
4. Server Setup: Use the Host builder pattern with proper DI configuration
5. Tools: Create at least one useful tool with proper attributes and descriptions; make the default example tool read only, clearly state in the Description attribute when a tool changes or deletes data so clients can ask the user for approval, and expose only the capabilities the use case needs
6. Error Handling: Include proper error handling and validation

Implementation Details

Basic Project Setup

• Use .NET 8.0 or later
• Create a console application
• Add necessary NuGet packages with --prerelease flag, pinned to one explicit prerelease version that is recorded and locked, with package sources limited to the official NuGet feed; review the chosen version before upgrading
• Configure logging to stderr

Server Configuration

• Use Host.CreateApplicationBuilder for DI and lifecycle management
• Configure AddMcpServer() with stdio transport
• Use WithToolsFromAssembly() for automatic tool discovery
• Include in the assembly only the tool classes that are intended and reviewed, and keep test or debug tools out of the build
• If prompts are needed, define prompt classes and methods with the SDK prompt attributes and register them for discovery, confirming the exact names against the installed package
• Ensure the server runs with RunAsync()

Tool Implementation

• Use [McpServerToolType] attribute on tool classes
• Use [McpServerTool] attribute on tool methods
• Add [Description] attributes to tools and parameters
• Support async operations where appropriate
• Include proper parameter validation
• Treat content returned by tools, such as file contents, database rows, and response bodies, as untrusted data; keep tool results size limited and return them as data only

Code Quality

• Follow C# naming conventions
• Include XML documentation comments
• Use nullable reference types
• Implement proper error handling with McpProtocolException (verify this and other type names against the installed, pinned ModelContextProtocol version before generating code)
• Return generic, sanitized error messages to clients and keep detailed messages, free of secrets, in stderr logs only
• Use structured logging for debugging; keep secrets, credentials, personal data, and full file or response contents out of logs, redact sensitive parameters, and default to Information level outside debugging
• Load API keys and connection strings from environment variables or a secret store, keep them out of source control, and keep them out of logs, tool results, and errors

Example Tool Types to Consider

• File operations (read and search by default, with opt in size limited write; restrict every path to a configured root directory, resolve full paths, reject paths outside the root including symbolic link escapes, and deny sensitive files such as keys and secret files)
• Data processing (transform, validate, analyze)
• External API integrations (HTTP requests to an allowlist of hosts over HTTPS only; block private, loopback, link local, and cloud metadata addresses; set timeouts and response size limits; treat responses as untrusted data)
• System operations (read only status checks; any command execution uses a fixed allowlist of programs and arguments, runs each program directly rather than through a shell, passes arguments as a list, applies timeouts, and asks the user for confirmation first)
• Database operations (parameterized queries only, with tool input passed as parameters rather than raw SQL; read only database account by default, with updates opt in and confirmed by the user)

Testing Guidance

• Explain how to run the server
• Provide example commands to test with MCP clients
• Include troubleshooting tips
• Include a security checklist to review before deployment, covering least privilege tools, input validation, path and host scoping, secret handling, and user confirmation for destructive actions

Generate a complete, well structured MCP server with comprehensive documentation and error handling, for human review and testing before deployment.