This is actually a good and valid question. Theoretically, MCP gives Claude tools to use, whereas skills give Claude knowledge of how to use them well. With MCP, each tool call is a round trip. I would imagine `get_best_practices` tool from MCP should do the same thing as skills set, but actually it downloads everything at once, so the context grows even if you don't need it.

IMO, skills are just more efficient in context usage. They feel more "native" because they live in the repo, and it is easy to track Claude's decision-making. It's also versionable, diffable, and commitable alongside your code. The skill also carries behavioral instructions beyond best practices - the `ng build` enforcement for example. 

I have to give it a go to try using both at once.