No Cliff at Three: Shadowing, Conflict, and Residency in Agent Skill Libraries

Agent Skills made it cheap to give an agent new procedures. A skill is a folder with a `SKILL.md` file. The specification describes progressive disclosure: name and description loaded at startup, the body only when the skill is activated. How a client assembles and keeps that context is its own choice, and Section 3 shows the choices differ. Anthropic's documentation says this lets a team "install many Skills without context penalty". The claim holds for skill bodies; each listed skill still costs roughly 50 to 100 tokens of catalog on every turn. This paper asks whether the claim holds for outcomes, and in particular whether there is a composition cliff: a point, sometimes asserted to fall at the third or fourth concurrent skill, after which each added skill makes the agent worse.

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