I don't think the idea of skills is quite snake oil. It seems you can change what LLM outputs next by what's called few-shot prompting or in-context learning: https://www.promptingguide.ai/techniques/fewshot
I disagree. Not all skills are useless. For example, I sometime use Qt for GUI projects and I have found their skills [0] very useful to improve the quality and performance of my projects. I their absence, I would each time have to direct the agents to find the docs or specific tools, wasting tokens and thus decreasing the quality of the output.
not that i know much about the effectiveness of these skill files, i find it odd to call something given for free "snake oil", which i thought referred to the sale of fraudulent products (to the benefit of the snake oil salesperson), typically around healthcare-related stuff.
I've found them useful for in house stuff where you are using a specific design system or architecture. But custom everything works best. Are that Claude works well on its own though at this point.
[0] https://github.com/TheQtCompanyRnD/agent-skills
Skills are literally just Markdown documents that get loaded into context when the /skill-name is invoked.