Can skills completely replace MCPs? For example, can a skill be configured to launch my local Python program in its own venv. I don’t want Claude to spend time spinning up a runtime

Skills only work if you have a code environment up and running and available for a coding agent to execute commands in.

You can absolutely have a skill that tells the coding agent how to use Python with your preferred virtual environment mechanism.

I ended up solving that in a slightly different way - I have a Claude hook that spits attempts to run "python" or "python3" and returns an error saying "use uv run instead".