The Microsoft Agent Framework recently added skills support, built around progressive disclosure (still in beta). The Give Your Agents Domain Expertise with Agent Skills devblog is an excellent introduction, so I won't re-tread the basics here.
If you've used skills in a coding agent, the idea is familiar: a skill is just a folder — a SKILL.md manifest plus reference documents and scripts — that the agent discovers and pulls in only when it needs to. Instead of stuffing every capability into the system prompt, the agent sees a lightweight catalog of skill names and descriptions, and loads the full content on demand. That's the whole point of progressive disclosure: an agent's context is a budget, and skills are a way to spend it lazily.
In practice that part just works: when a request matches a skill, the model is nudged to call the built-in load_skill tool, and the framework returns the skill's full content for the model to use. Triggering and loading behave exactly as advertised.
But spending the budget is only half the story. Once a skill's content is loaded, where does it actually live — and is it ever dropped? The docs are silent on this, and it's the question the rest of this post digs into.
