Using Claude Code: The Unreasonable Effectiveness of HTML
Manifesto-style article by **Thariq Shihipar** (Engineer & serial entrepreneur, Claude Code team at Anthropic) announcing a **change in the default output format for agents**: replacing **Markdown with HTML**. Thesis: Markdown has been the dominant format between humans and agents (simple, portable, editable, readable) but has become **a bottleneck** as agents produce longer and richer artifacts (specs, plans, reports, code review). Beyond ~100 lines, no one reads a Markdown file anymore. HTML solves six limitations simultaneously: **information density** (tables, CSS, SVG, scripts, canvas, images), **visual clarity** (navigable, mobile-responsive layout), **ease of sharing** (an S3 link directly openable in a browser), **two-way interactivity** (sliders, knobs, "copy as JSON/prompt" buttons to loop back into Claude Code), **native contextual ingestion** (Claude Code reads the codebase + MCP Slack/Linear + git history + Chrome) and **enjoyment** (the author explicitly claims *"it's joyful"*). Five canonical uses detailed: (1) **specs/plans/exploration** in a comparative grid, (2) **PR review** with inline annotated diff, (3) **design & prototypes** with animation sliders, (4) **reports/research/learning** (the author had a prompt-caching explainer generated from git history), (5) **custom throwaway editors** (drag-and-drop of Linear tickets, feature-flag editors, side-by-side prompt-tuner) that produce a re-injectable "copy as markdown/diff/JSON" export. Explicit anti-pattern: *"I'm a little bit afraid that people will read this article and turn it into a /html skill"* — the author **rejects premature skill-ification**, recommending prompting from scratch ("make a HTML file"). Pragmatic FAQ: token cost absorbed by **Opus 4.7**'s 1MM context, 2-4× longer generation, noisy HTML diffs (a real downside), style kept in check via a reference HTML design system.
Thariq Shihipar (Engineer & serial entrepreneur, équipe Claude Code chez Anthropic — site : thariqs.github.io/html-effectiveness ; X : @trq212)