Simon Willison — 2026-05-08#

Highlight#

Simon re-evaluates his long-standing habit of asking LLMs for Markdown output, sparked by Anthropic’s Thariq Shihipar advocating for the rich capabilities of HTML. He tests this out practically by using his llm CLI to generate an interactive HTML explanation of a newly discovered Linux security exploit.

Posts#

[Using Claude Code: The Unreasonable Effectiveness of HTML] · Source Simon reflects on a piece by Thariq Shihipar (from Anthropic’s Claude Code team) that argues for requesting HTML instead of Markdown from Claude. While Markdown’s token-efficiency was a strict necessity during the 8,192-token GPT-4 days, modern LLMs can leverage HTML to output SVG diagrams, interactive widgets, and rich in-page navigation. Simon tests this technique by piping an obfuscated Python exploit from copy.fail into gpt-5.5 via his llm CLI tool, successfully prompting the model to generate a fully styled, interactive HTML explanation of the code.

Simon Willison — Week of 2026-05-08 to 2026-05-15#

Highlight of the Week#

The standout development this week is Simon’s rapid adaptation to the latest frontier model capabilities, most notably releasing llm 0.32a2 to expose and visualize the new interleaved reasoning tokens of GPT-5 class models directly in the terminal. This perfectly pairs with his hands-on explorations of embedding LLM calls deeply into developer workflows, such as executing prompts via script shebangs and leveraging models to output rich HTML rather than just Markdown.