Using Claude Code: The Unreasonable Effectiveness of HTML
AI Summary
Simon Willison's link-blog post reacting to Thariq Shihipar's piece arguing for HTML over Markdown as Claude Code's output format, since HTML lets Claude drop in SVG diagrams, interactive widgets, and in-page navigation. Willison notes this changed his own default (set since the GPT-4 8k-token era) and shares his own experiment asking GPT-5.5 to generate a rich interactive HTML explainer of a real Linux security exploit.
Original excerpt
Posted 8th May 2026 by Simon Willison. "Using Claude Code: The Unreasonable Effectiveness of HTML" is a thought-provoking piece by Thariq Shihipar, who is on the Claude Code team at Anthropic, advocating for HTML over Markdown as an output format to request from Claude. The article is crammed with examples and prompt suggestions, including one Willison quotes directly: "Help me review this PR by creating an HTML artifact that describes it. I'm not very familiar with the streaming/backpressure logic so focus on that. Render the actual diff with inline margin annotations, color-code findings by severity and whatever else might be needed to convey the concept well."
Willison writes that he'd…
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Simon Willison's link-blog post reacting to Thariq Shihipar's piece arguing for HTML over Markdown as Claude Code's output format, since HTML lets Claude drop in SVG diagrams, interactive widgets, and in-page navigation. Willison notes this changed his own default (set since the GPT-4 8k-token era)…
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"Using Claude Code: The Unreasonable Effectiveness of HTML" was written by Simon Willison. It is curated in the Claude Code vault on Burn 451, which covers agentic coding with claude.
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Content attributed to the original author (Simon Willison). Burn 451 curates publicly available writing as a reading index. For removal requests, contact @hawking520.