Narrowly focused semantics/affordances (for both LLM and users/future package managers/communities, ease of redistribution and context management:

- skills are plain files that are injected contextually whereas prompts would come w the overhead of live, running code that has to be installed just right into your particular env, to provide a whole mcp server. Tbh prompts also seem to be more about literal prompting, too

- you could have a thousand skills folders for different softwares etc but good luck with having more than a few mcp servers that are loaded into context w/o it clobbering the context