How to Use Claude Code: The Surprising Utility of HTML

The Claude Code team has started preferring HTML over Markdown when agents communicate with humans. Their judgment is that Markdown's readability drops in long documents, and it lacks expressiveness for things like color, diagrams, and interactivity, making it hard to actually produce output that's easy to read and share.

HTML has high information density. It can hold tables, CSS-based design, SVG, code snippets with scripts, interactive elements like buttons and sliders, and even spatial representation using absolute positioning or canvas—allowing Claude to visualize the information it has read much more richly.

The advantages in terms of reading and sharing are also clear. A Markdown document over 100 lines is hard to read all the way through, but HTML is easy to navigate with tab structures, links, and responsive layouts, and can be opened directly in a browser and shared via link. Combined with Claude Code's strengths—its data-gathering capabilities across the file system, MCP, Slack, Linear, browser, and git history—this is especially advantageous for organizing research findings, design proposals, or PR descriptions into document form.

Use cases include the following.

• Planning and exploration: Compare multiple design proposals on a single screen, and create implementation plans that include mockups and code snippets.
• Code review and understanding: Visualize diffs, comments, flowcharts, and module descriptions to explain or review PRs.
• Design and prototyping: Add sliders, buttons, and animations to run interactive design experiments.
• Reports and learning: Combine code, Slack, and internet sources to create easy-to-read research reports or incident reports.
• Custom editors: Build one-off UIs for tasks like organizing tickets, editing feature flags, or tuning prompts, then copy the results back into JSON or a prompt.

The key point is that HTML doesn't completely replace Markdown—rather, it's an output format that helps Claude explain larger tasks better and makes them easier to review. When needed, you can simply ask "make an HTML file" or "make an HTML artifact" to get started right away, and in the long run, it's suggested that this could be expanded into a skill for recurring patterns.