That's exactly what Claude Skills do [0], and while this tool search appears to be distinct, I do think that they're on the way to integrating MCP and Skills.
Which is basically exactly as much effort as what I was doing previously of having prewritten sub-prompts/agents in files and loading up the file each time I want to use it.
I don't think this is an issue with how I'm writing skills, because it includes skill like the Skill Creator from Anthropic.
I've mostly been working on smaller projects so I never need to compact. And skills are definitely not working even on the initial prompt of a new session.