ASP.NET Core Web Api automatic help pages

Well, modern way is to use Swashbuckle NuGet Package:

dotnet add package Swashbuckle.AspNetCore

It takes care about generating JSON file with documentation of your .NET API.

In code you need to make following adjustments:

builder.Services.AddSwaggerGen(options =>
{
    // Optional: Include XML comments
    var xmlFilename = $"{System.Reflection.Assembly.GetExecutingAssembly().GetName().Name}.xml";
    options.IncludeXmlComments(Path.Combine(AppContext.BaseDirectory, xmlFilename));
});

var app = builder.Build();

// Enable Swagger middleware
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI(c =>
    {
        c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
        c.RoutePrefix = string.Empty; // Serve Swagger UI at app root
    });
}

Now you are able to go to swagger page /swagger and access also underlaying JSON documentation file /swagger/v1/swagger.json.

Also, for documentation generation there is also Microsoft package that can be used for that. Please take a look at Generate OpenAPI documents

To use it you need nuget package

dotnet add package Microsoft.AspNetCore.OpenApi

with following changes in code:

builder.Services.AddOpenApi();

var app = builder.Build();

if (app.Environment.IsDevelopment())
{
    app.MapOpenApi();
    app.UseSwaggerUI(options => options.SwaggerEndpoint("/openapi/v1.json", "Open API"))
}

Then, in swagger UI you need to add path to Open API docs

References: Get started with Swashbuckle and ASP.NET Core

For this instance, I used the Microsoft.AspNetCore.Mvc.ApiExplorer to inject IApiDescriptionGroupCollectionProvider, and tryaddenumerable for IApiDescriptionProvider, DefaultApiDescriptionProvider

I then created a help controller which provided me a list of string from looping into ApiDescriptionGroups.Items[0] then getting each relativepath. Also checking if there are ParameterDescriptions then getting all its name to stringbuilder to provide me the API description. Not bad but hehe. That's what the old man wants me todo. Hahaha.

EDIT: You can discard the tryaddenumerable for IApiDescriptionProvider, DefaultApiDescriptionProvider as for this example i am not using the provider to be expanded in the api documentation entities.