Create or Update Claude Code Skill

VerifiedCaution

Guidelines for creating or updating Claude Code skills, covering frontmatter, content rules, and mode detection.

Sby Skills Guide Bot
DevelopmentIntermediate
208/7/2026
Claude Code
#skill-management#skill-authoring#claude-code#workflow

Recommended for

Our review

Creates or updates a Claude Code skill by converting the current conversation into a SKILL.md file with appropriate frontmatter and rules.

Strengths

  • Encourages concise, behavior-focused skill files
  • Provides clear frontmatter guidance
  • Differentiates create vs update modes explicitly
  • Emphasizes token cost efficiency

Limitations

  • Claude Code-specific, not portable to other tools
  • Requires manual judgment for mode and frontmatter
  • No automated validation of the generated SKILL.md
When to use it

When you need to persist a new reusable behavior or update an existing skill while working in Claude Code.

When not to use it

When the skill is already fully written or when you are only discussing code without changing skill definitions.

Security analysis

Caution
Quality score92/100

The skill instructs the AI to create directories and write files, which are powerful operations but legitimate for the purpose of managing skill files. It does not contain destructive or exfiltrating commands.

Findings
  • Uses file system operations (mkdir, write) which could be misused if arguments are untrusted.

Examples

Create a code review skill
Create a skill named code-review-checklist with guidelines for reviewing pull requests.
Update a skill with a new rule
Update the skill typescript-error-fixes with the new rule about null checks.
Modify an existing skill
Add a new rule to existing skill commit-message about conventional commits.

Create or update a skill based on the current conversation.

The first word of $ARGUMENTS is the skill name (kebab-case). The rest is an optional note about what to add or change.


Step 1 — Detect mode

Check whether .claude/skills/$0/SKILL.md already exists.

  • Existsupdate mode: read the current file, then go to Step 3.
  • Does not existcreate mode: go to Step 2.

Step 2 — Determine frontmatter (create only)

Decide the correct frontmatter based on what the skill does:

description — one sentence: what the skill does + when Claude should auto-load it. Put the key trigger phrase first (budget is 1,536 chars).

paths — set only if the skill is scoped to specific files. Use glob patterns:

  • Design system / theme work → @soroush.tech/design-system/**
  • All TypeScript → **/*.ts,**/*.tsx
  • Omit for project-wide knowledge

argument-hint — short label shown in autocomplete, e.g. [filename] or [component-name].

disable-model-invocation: true — add only if this is a manual workflow with side effects (deploy, commit, send). Reference knowledge should NOT have this.

user-invocable: false — add only if users should never call it directly (pure background context).


Step 3 — Write content

Rules for skill content:

  • Reference skills (conventions, patterns, style guides): state the rule + one ✗/✓ code pair. No prose explaining why — the example shows it.
  • Task skills (step-by-step actions): numbered steps, imperative verbs, no explanation.
  • Keep SKILL.md under 500 lines.
  • Every line is a recurring token cost — cut anything that doesn't change Claude's behavior.
  • End with: If $ARGUMENTS names a file, read it and apply the rules. Otherwise apply to the code being discussed. (for reference skills only).

Update mode: add the new rule or change to the appropriate section. Do not touch unrelated rules. Remove any rule made obsolete by the change.


Step 4 — Write the file

For create: run mkdir -p .claude/skills/$0 then write .claude/skills/$0/SKILL.md.

For update: write the updated .claude/skills/$0/SKILL.md.

Confirm what was created or changed. If a new paths scope was set, mention which files will trigger it.

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