I've been going heavily in the direction of globally configured MCP servers and composite agents with copilot, and just making my own MCP servers in most cases.

Then all I have to do is let the agents actually figure out how to accomplish what I ask of them, with the highly scoped set of tools and sub agents I give them.

I find this works phenomenally, because all the .agent.md file is, is a description of what the tools available are. Nothing more complex, no LARP instructions. Just a straightforward 'here's what you've got'.

And with agents able to delegate to sub agents, the workflow is self-directing.

Working with a specific build system? Vibe code an MCP server for it.

Making a tool of my own? MCP server for dev testing and later use by agents.

On the flipside, I find it very questionable what value skills and reusable prompts give. I would compare it to an architect playing a recording of themselves from weeks ago when talking to their developers. The models encode a lot of knowledge, they just need orientation, not badgering, at this point.