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Skill reference

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Frontmatter

Per the Agent Skills specification:

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Name Rules

  • 1-64 characters
  • Lowercase letters, numbers, hyphens only
  • No leading/trailing hyphens
  • No consecutive hyphens
  • Must match parent directory name
Valid: pdf-processing, data-analysis, code-review Invalid: PDF-Processing, -pdf, pdf--processing

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Description Best Practices

The description determines when the agent loads the skill. Be specific. Good:
Poor:

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Validation

Atomic validates skills against the Agent Skills standard. Most issues produce warnings but still load the skill:
  • Name doesn’t match parent directory
  • Name exceeds 64 characters or contains invalid characters
  • Name starts/ends with hyphen or has consecutive hyphens
  • Description exceeds 1024 characters
Unknown frontmatter fields are ignored. Declared skills with missing descriptions are not loaded. Malformed SKILL.md files and SKILL.md files without a description produce warnings and are not loaded. Other Markdown files without valid skill frontmatter are ignored. Name collisions (the same name from different real files) produce diagnostics and keep the existing first-winner precedence for /skill:name. Atomic also retains the other files as source-qualified candidates as described in Skill Commands.