alt Hacker NewsYes, it happens on startup of a fresh Claude Code / Codex CLI session. They effectively get pasted into the system prompt.
Reading a few dozen files takes on the order of a few ms. They add enough tokens per skill to fit the metadata description, so probably less than 100 for each skill.
So when it says:
> The body can contain any Markdown; it is not injected into context.
It just means it's not injected into the context until the skill is used or it's never injected into the context?
https://github.com/openai/codex/blob/main/docs/skills.md