Simon Willison

Simon Willison read Anthropic's Skills as a bigger deal than MCP in an October 2025 post, and the reasoning was structural: a Skill is a folder of Markdown instructions, optional scripts and resources, loaded when relevant. Its only infrastructure requirement is a coding environment with filesystem access. He had already gone looking for the mechanism directly, asking Claude to describe its own capabilities and then to zip up `/mnt/skills`, which turned out to hold Python scripts for docx, PDF, pptx and xlsx manipulation (pypdf handles PDF form filling). He published the contents as `simonw/claude-skills`. He predicted a "cambrian explosion" of Skills.

Two other threads run through his appearances. He treats `vibe coding` as a democratizing force, arguing it lets people build their own tools without a computer science degree, a position Shawn "swyx" Wang contests on grounds of the unfinished last 20 percent. And he named the "Trifecta Mortelle" for AI agents: access to private data, exposure to untrusted content, ability to exfiltrate. Martin Fowler cites it to conclude that an agentic browser extension cannot be built safely.

The July 2026 note is the smallest and the most concrete. Following advice from Jesse Vincent, Willison told `Claude Code` to pick a lower-power model and run coding tasks in a subagent. Claude Code wrote itself a memory file codifying the split. His verdict: "I'm getting a ton of work done and my Fable allowance is shrinking less quickly than before."