Thariq Shihipar (타리크 시히파르), who is in charge of Claude Code at Anthropic, has posted a piece calling for AI agents to switch their output format from Markdown to HTML.

He said Markdown has become a key file format for communicating with agents, but its limitations are also clear.

"Markdown files longer than 100 lines are hard to read. You need visual expression such as visualisation, colour and diagrams, but Markdown has limits, and sharing is inconvenient. People also edit files directly less often, and editing is often delegated to Claude, so Markdown's biggest advantage has disappeared," he said.

Shihipar cited four advantages of HTML.

First is information density. HTML can represent tables, CSS design, SVG illustrations, JavaScript interactions, spatial data and images. He said the inefficiency of Claude roughly expressing colours with Unicode characters or drawing ASCII diagrams in Markdown disappears in HTML.

Second is readability. HTML can visually structure content with tabs, illustrations and links. It can also be mobile responsive. He stressed that unlike long Markdown documents that are hard for others in an organisation to read, HTML is far more likely to actually be read.

Third is ease of sharing. Markdown is not natively rendered by browsers, so it must be sent as an attachment. HTML can be shared with a single link if uploaded to a place such as S3. "The likelihood that colleagues will actually open planning documents, reports and PR manuals becomes much higher," he said.

Fourth is two-way interaction. In an HTML document, sliders or buttons can be added to adjust design options directly and paste the results back into Claude Code. He said this is not possible in Markdown.

Shihipar said he uses HTML for various purposes, including planning, code reviews, design prototypes, reports and custom editing interfaces. In the planning stage, he places draft options for multiple directions side by side in a single HTML file for comparison at a glance.

For code reviews, he said an HTML-made code guide is better than GitHub's default diff view showing code changes, and he attaches an HTML guide to each pull request. For custom editing interfaces, he creates one-off editing tools in HTML, such as draggable cards and form-based settings editors, and always adds a button at the end to copy the results.

He explained that he uses Claude Code because it can create HTML by ingesting a range of contexts, including the file system, MCP (Slack, Linear and others), Git history and the browser.

There are disadvantages as well. HTML takes 2 to 4 times longer to generate than Markdown, and diffs are complex in version control. It also uses more tokens. Still, he said, "Using HTML makes me much more deeply involved in what Claude does. I was worried that not reading planning documents in detail would mean having to leave decisions to Claude, but now I understand what Claude is doing much better than before."

Document format 'Markdown' - what is it?... Government and companies adopt it one after another as AI spreads