Added HTML → Markdown conversion tool

[AezanPathan]

Purpose

• Adds a new tool class HtmlToMarkdownTool to convert HTML back to Markdown.
  This allows users to perform two-way conversion between Markdown and HTML using separate tools (MarkdownToHtmlTool and HtmlToMarkdownTool).

Does this introduce a breaking change?

[ ] Yes
[x] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[x] New feature to existing sample
[ ] New sample
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

README updated?

The top-level readme for this repo contains a link to each sample in the repo. If you're adding a new sample did you update the readme?

[ ] Yes
[x] No
[ ] N/A

How to Test

• Get the code

git clone https://github.com/AezanPathan/mcp-dotnet-samples.git
cd mcp-dotnet-samples
git checkout feature/reverse-markdown

• Test the code

Use the HtmlToMarkdownTool.ConvertAsync method to convert an HTML string back to Markdown.

Verify that HTML input is correctly converted to Markdown output.

Existing ConvertAsync method for Markdown → HTML should continue to work without changes.

What to Check

Verify that the following are valid

• HTML content is properly converted back to Markdown using HtmlToMarkdownTool.

• Existing Markdown → HTML conversion still works.

• No errors or exceptions occur when using either conversion method.

Other Information

• Uses the ReverseMarkdown NuGet package for HTML → Markdown conversion.

• Tested locally and works alongside the existing Markdown → HTML pipeline.

[AezanPathan]

@microsoft-github-policy-service agree

[justinyoo]

@AezanPathan Thanks for this PR! However, I'd like you to add another tool class like HtmlToMarkdownTool.cs and put your logic there. Would you please take a look please?

[AezanPathan]

Hi @justinyoo, I’ve updated the PR — moved the logic into the new HtmlToMarkdownTool class as suggested and adjusted the PR description accordingly. Please review when you get a chance. Thanks for the guidance!