Interview Bank

Agent Skills in 7 Days: Turn Experience Into Reusable Capability

D1 What Skills Are: the SKILL.md Spec, Directory Layout, and Three-Stage Progressive Disclosure

• What hard constraints does the spec put on the name and description fields, and why is name so tightly constrained?SKILL.md 的 name 与 description 有哪些硬性约束？规范为什么要把 name 卡得这么死？

  Common in ChinaCommon overseasIntermediate#agent-skills#spec

  How to reason about it · think before answering

  1. It looks like spec recall, but the real question is the why. Listing the constraints is a pass; explaining which engineering problem they prevent is the differentiator.
  2. Name has five constraints: one to sixty-four characters, lowercase letters digits and hyphens only, no leading or trailing hyphen, no consecutive hyphens, and it must match the parent directory name.
  3. Description has two: one to one thousand twenty-four characters, and it must convey both what the skill does and when to use it.
  4. The reason name is strict: it is the skill's identity across the ecosystem, feeding directory lookup, namespacing, slash-command invocation and collision precedence. One casing mismatch becomes an installed but uncallable skill.
  5. Mention the real-world wrinkle: many clients deliberately relax the name-matches-directory rule and only warn, so a skill can work locally and vanish under a stricter implementation.
  6. Expected follow-up: what if the description runs to a thousand characters? You pay for it every session. Twenty maxed-out descriptions cost eight thousand tokens of catalog, so shorten the text rather than dropping skills.

  分析过程 · 先想清楚再作答

  1. 这题看着像背规范，其实题眼在后半句「为什么」。能把约束背全只算及格，能说出这些约束是为了解决什么工程问题才是加分项。
  2. 先把 name 的五条约束数完：长度一到六十四个字符、只能用小写字母数字和连字符、不能以连字符开头或结尾、不能有连续两个连字符、必须与父目录名一致。
  3. 再给 description 的两条：长度一到一千零二十四个字符；内容上要同时说清做什么和什么时候用，而不是只说做什么。
  4. 解释「为什么卡这么死」：name 是这个 skill 在整个生态里的唯一标识，要拼进目录名、命名空间、斜杠命令，还要在两个 skill 撞名时用来判优先级。任何一处大小写或分隔符不一致，都会变成一个很难查的「装了却调不到」。
  5. 补一个真实的坑：很多客户端在实现时故意放宽了「name 等于目录名」这条，不一致只打警告仍然加载。于是你本地一切正常，换个严格实现就整个消失。
  6. 可预期的追问是「description 写到一千个字符会怎样」。答案是它每次会话都要付一遍，二十个 skill 都写满上限，光目录就要八千 token，这时候该做的是把描述写短而不是删 skill。

  Key points

  • Name: one to sixty-four characters, lowercase alphanumerics and hyphens, no leading or trailing hyphen, no double hyphens, must equal the directory name.
  • Description: one to one thousand twenty-four characters, stating both what it does and when to use it.
  • Name is strict because it is the skill's identity for lookup, namespacing, invocation and collision precedence.
  • Many clients validate name leniently, so working locally does not guarantee working elsewhere.
  • The description is a fixed per-session cost, so keep it as short as it can be while still triggering.

  答题要点

  • name：一到六十四字符、小写字母数字与连字符、首尾不能是连字符、不能有连续连字符、必须等于父目录名。
  • description：一到一千零二十四字符，必须同时说清做什么与什么时候用。
  • name 卡死是因为它是唯一标识，要参与目录查找、命名空间、命令调用与撞名优先级。
  • 很多客户端对 name 做宽松校验，本地能跑不代表换个客户端也能跑。
  • description 是每次会话都要付的固定开销，能短则短。