Skill

A Skill is a folder rather than a markdown file: instructions, scripts, resources, configuration and hooks that the agent discovers and manipulates. Thariq Shihipar put that correction first when he described how Anthropic's Claude Code team uses skills internally, on 3 June 2026, alongside a taxonomy of nine categories observed in practice, from library and API reference to runbooks and infrastructure operations. His advice on content is subtractive: Claude already knows how to code and can read the codebase, so a skill should document what contradicts default behavior. The highest-signal section, he writes, is Gotchas, fed by failure points actually encountered. The description field is written for the model: it states when to trigger the skill, not what the skill contains. Configuration runs through a setup flow that stores parameters in `config.json` or asks the user via AskUserQuestion.

Hugo Lassiège arrives at a similar shape from a solo practice. In his 28 July 2026 account of his usine logicielle, skills are what the agent can do deterministically, sitting between what it knows (context, memory, code graph) and what stops it (hooks, tests, gates). He keeps about thirty, creates one at the third repetition, and finds the skills covering a multi-file procedure pay best. A rule serves as a routing table toward skills to be opened only when needed.

Hooks conditionnels narrow what the agent may do for the duration of a skill. Lassiège names the part still unsolved: for lack of packaging, skills get copy-pasted.