Guide for creating and reviewing skills. This skill should be used when users want to create a new skill, review an existing skill for quality, or optimize a skill that extends Claude's capabilities with specialized knowledge, workflows, or tool integrations.
Guide for creating and reviewing skills. This skill should be used when users want to create a new skill, review an existing skill for quality, or optimize a skill that extends Claude's capabilities with specialized knowledge, workflows, or tool integrations.
Skill Creator
This skill provides guidance for creating effective skills.
About Skills
Skills are modular, self-contained packages that extend Claude's capabilities by providing specialized knowledge, workflows, and tools. Think of them as "onboarding guides" for specific domains or tasks—they transform Claude from a general-purpose agent into a specialized agent equipped with procedural knowledge that no model can fully possess.
Skills follow the Agent Skills open standard, with Claude Code extensions for invocation control, subagent execution, and dynamic context injection.
What Skills Provide
Specialized workflows - Multi-step procedures for specific domains
Tool integrations - Instructions for working with specific file formats or APIs
Domain expertise - Company-specific knowledge, schemas, business logic
Bundled resources - Scripts, references, and assets for complex and repetitive tasks
Anatomy of a Skill
Every skill consists of a required SKILL.md file and optional bundled resources:
Metadata Quality: The name and description in YAML frontmatter determine when Claude will use the skill. Be specific about what the skill does and when to use it. Use the third-person (e.g. "This skill should be used when..." instead of "Use this skill when...").
Frontmatter Fields:
Field
Required
Description
name
No
Display name (max 64 chars, lowercase + hyphens). Defaults to directory name.
description
Recommended
What the skill does and when to use it (max 1024 chars).
argument-hint
No
Hint shown during autocomplete (e.g., [issue-number]).
disable-model-invocation
No
true = only user can invoke via /name.
user-invocable
No
false = hide from / menu (Claude-only background knowledge).
allowed-tools
No
Restrict tools when skill is active (e.g., Read, Grep, Glob).
model
No
Model override when skill is active.
context
No
fork = run in isolated subagent.
agent
No
Subagent type: Explore, Plan, general-purpose, or custom from .claude/agents/.
(Replace EXCLAIM with the exclamation mark character and BACKTICK with the backtick character in real skills)
When this skill runs:
Each exclamation-backtick command executes immediately (before Claude sees anything)
The output replaces the placeholder in the skill content
Claude receives the fully-rendered prompt with actual data
This is preprocessing, not something Claude executes. Claude only sees the final result.
Invocation Control
By default, both users and Claude can invoke any skill. Two frontmatter fields control this:
Frontmatter
User can invoke
Claude can invoke
In context
(default)
Yes
Yes
Description always visible
disable-model-invocation: true
Yes
No
Description hidden from Claude
user-invocable: false
No
Yes
Description always visible
When to use each:
disable-model-invocation: true: For workflows with side effects (deploy, commit, send-message). Prevents Claude from triggering automatically.
user-invocable: false: For background knowledge that isn't a meaningful command (e.g., legacy-system-context). Claude should know this when relevant, but /legacy-system-context isn't useful for users.
Subagent Integration
Add context: fork to run skills in isolation. The skill content becomes the subagent's prompt (no conversation history access).
Note:context: fork only makes sense for skills with explicit instructions. Guidelines-only skills (e.g., "use these API conventions") receive no actionable prompt and return without meaningful output.
Skill Locations
Where a skill is stored determines who can use it:
Location
Path
Applies to
Priority
Enterprise
Managed settings
All org users
Highest
Personal
~/.claude/skills/<name>/SKILL.md
All your projects
High
Project
.claude/skills/<name>/SKILL.md
This project only
Medium
Plugin
<plugin>/skills/<name>/SKILL.md
Where plugin enabled
Namespaced
When skills share the same name, higher-priority locations win. Plugin skills use plugin-name:skill-name namespace, so they cannot conflict.
Nested discovery: When editing files in subdirectories (e.g., packages/frontend/), Claude Code also discovers skills from nested .claude/skills/ directories. This supports monorepos where packages have their own skills.
Legacy commands: Files in .claude/commands/ still work with the same frontmatter. Skills are recommended since they support additional features like supporting files.
Bundled Resources (optional)
Scripts (scripts/)
Content Type: Code - Executable code (Python/Bash/etc.) for tasks that require deterministic reliability or are repeatedly rewritten.
When to include: When the same code is being rewritten repeatedly or deterministic reliability is needed
Example: scripts/rotate_pdf.py for PDF rotation tasks
Benefits: Token efficient, deterministic, script code never enters context - only output does
Key advantage: A 200-line script only costs ~20 tokens (the output), not 2000+ tokens (the code)
Note: Scripts may still need to be read by Claude for patching or environment-specific adjustments
References (references/)
Content Type: Instructions - Documentation and reference material intended to be loaded as needed into context to inform Claude's process and thinking.
When to include: For documentation that Claude should reference while working
Examples: references/finance.md for financial schemas, references/mnda.md for company NDA template, references/policies.md for company policies, references/api_docs.md for API specifications
Use cases: Database schemas, API documentation, domain knowledge, company policies, detailed workflow guides
Benefits: Keeps SKILL.md lean, loaded only when Claude determines it's needed
Best practice: If files are large (>10k words), include grep search patterns in SKILL.md
Avoid duplication: Information should live in either SKILL.md or references files, not both. Prefer references files for detailed information unless it's truly core to the skill—this keeps SKILL.md lean while making information discoverable without hogging the context window. Keep only essential procedural instructions and workflow guidance in SKILL.md; move detailed reference material, schemas, and examples to references files.
Assets (assets/)
Content Type: Resources - Files not intended to be loaded into context, but rather used within the output Claude produces.
When to include: When the skill needs files that will be used in the final output
Examples: assets/logo.png for brand assets, assets/slides.pptx for PowerPoint templates, assets/frontend-template/ for HTML/React boilerplate, assets/font.ttf for typography
Use cases: Templates, images, icons, boilerplate code, fonts, sample documents that get copied or modified
Benefits: Separates output resources from documentation, enables Claude to use files without loading them into context
Progressive Disclosure Design Principle
Skills use a three-level loading system to manage context efficiently:
Level
When Loaded
Token Cost
Content
Level 1: Metadata
Always (at startup)
~100 tokens per Skill
name and description from YAML frontmatter
Level 2: Instructions
When Skill is triggered
Under 5k tokens
SKILL.md body with instructions and guidance
Level 3+: Resources
As needed
Effectively unlimited*
Bundled files executed via bash without loading into context
*Scripts are executed without loading code into context (only output enters context). Reference files and assets are loaded only when Claude explicitly accesses them via bash commands.
Key insight: You can install dozens of Skills with minimal context penalty. Claude only knows each Skill exists and when to use it until one is triggered.
Context budget: Skill descriptions are loaded into context so Claude knows what's available. If you have many skills, they may exceed the character budget (default 15,000 characters). Run /context to check for excluded skills. To increase the limit, set SLASH_COMMAND_TOOL_CHAR_BUDGET environment variable.
The Skills Filesystem Architecture
Skills exist as directories on the local filesystem, and Claude interacts with them using bash commands and file operations.
How Claude accesses Skill content:
Reading instructions: When a Skill is triggered, Claude reads SKILL.md from the filesystem via bash, bringing its instructions into context
Loading references: If instructions reference other files (like references/api_docs.md or database schemas), Claude reads those files using additional bash commands
Executing scripts: When instructions mention executable scripts, Claude runs them via bash. Only the script output enters context, not the code itself
What this enables:
On-demand file access: Claude reads only the files needed for each task. A Skill can include dozens of reference files, but if your task only needs one schema, Claude loads just that file. The rest consume zero tokens
Efficient script execution: When Claude runs validate_form.py, only the output consumes tokens, not the 200-line script. This makes scripts far more efficient than having Claude generate equivalent code on the fly
No practical limit on bundled content: Because files don't consume context until accessed, Skills can include comprehensive documentation, datasets, examples, or reference materials without context penalty
Example workflow:
1. User: "Process this PDF and extract tables"
2. Claude: bash: read pdf-skill/SKILL.md
3. SKILL.md mentions scripts/extract_tables.py
4. Claude: bash: python scripts/extract_tables.py input.pdf
5. Script output: "Extracted 3 tables: [table data...]"
6. Claude proceeds using the extracted data (script code never entered context)
Skill Creation Process
To create a skill, follow the "Skill Creation Process" in order, skipping steps only if there is a clear reason why they are not applicable.
Step 1: Understanding the Skill with Concrete Examples
Skip this step only when the skill's usage patterns are already clearly understood. It remains valuable even when working with an existing skill.
To create an effective skill, clearly understand concrete examples of how the skill will be used. This understanding can come from either direct user examples or generated examples that are validated with user feedback.
For example, when building an image-editor skill, relevant questions include:
"What functionality should the image-editor skill support? Editing, rotating, anything else?"
"Can you give some examples of how this skill would be used?"
"I can imagine users asking for things like 'Remove the red-eye from this image' or 'Rotate this image'. Are there other ways you imagine this skill being used?"
"What would a user say that should trigger this skill?"
To avoid overwhelming users, avoid asking too many questions in a single message. Start with the most important questions and follow up as needed for better effectiveness.
Conclude this step when there is a clear sense of the functionality the skill should support.
Step 2: Planning the Reusable Skill Contents
To turn concrete examples into an effective skill, analyze each example by:
Considering how to execute on the example from scratch
Identifying what scripts, references, and assets would be helpful when executing these workflows repeatedly
Example: When building a pdf-editor skill to handle queries like "Help me rotate this PDF," the analysis shows:
Rotating a PDF requires re-writing the same code each time
A scripts/rotate_pdf.py script would be helpful to store in the skill
Example: When designing a frontend-webapp-builder skill for queries like "Build me a todo app" or "Build me a dashboard to track my steps," the analysis shows:
Writing a frontend webapp requires the same boilerplate HTML/React each time
An assets/hello-world/ template containing the boilerplate HTML/React project files would be helpful to store in the skill
Example: When building a big-query skill to handle queries like "How many users have logged in today?" the analysis shows:
Querying BigQuery requires re-discovering the table schemas and relationships each time
A references/schema.md file documenting the table schemas would be helpful to store in the skill
To establish the skill's contents, analyze each concrete example to create a list of the reusable resources to include: scripts, references, and assets.
Step 3: Initializing the Skill
At this point, it is time to actually create the skill.
Skip this step only if the skill being developed already exists, and iteration or packaging is needed. In this case, continue to the next step.
When creating a new skill from scratch, always run the init_skill.py script. The script conveniently generates a new template skill directory that automatically includes everything a skill requires, making the skill creation process much more efficient and reliable.
Generates a SKILL.md template with proper frontmatter and TODO placeholders
Creates example resource directories: scripts/, references/, and assets/
Adds example files in each directory that can be customized or deleted
After initialization, customize or remove the generated SKILL.md and example files as needed.
Step 4: Edit the Skill
When editing the (newly-generated or existing) skill, remember that the skill is being created for another instance of Claude to use. Focus on including information that would be beneficial and non-obvious to Claude. Consider what procedural knowledge, domain-specific details, or reusable assets would help another Claude instance execute these tasks more effectively.
Start with Reusable Skill Contents
To begin implementation, start with the reusable resources identified above: scripts/, references/, and assets/ files. Note that this step may require user input. For example, when implementing a brand-guidelines skill, the user may need to provide brand assets or templates to store in assets/, or documentation to store in references/.
Also, delete any example files and directories not needed for the skill. The initialization script creates example files in scripts/, references/, and assets/ to demonstrate structure, but most skills won't need all of them.
Populating References from Documentation (Optional)
For skills based on existing frameworks, libraries, or tools with online documentation, use Skill_Seekers (v2.0.0+) to automatically scrape and organize documentation into the references/ directory. Skill_Seekers now supports unified multi-source scraping, combining documentation websites, GitHub repositories, and PDF files into comprehensive reference materials.
When to use this approach:
Building skills for frameworks with comprehensive online docs (React, Django, FastAPI, etc.)
Creating skills for game engines (Godot, Unity)
Documenting APIs or libraries with web-based documentation
Extracting API references directly from GitHub source code
Alternative: For simpler needs or when documentation is not web-based, manually create reference files in the references/ directory.
For detailed Skill_Seekers documentation, see references/documentation-scraping.md.
Update SKILL.md
Writing Style: Write the entire skill using imperative/infinitive form (verb-first instructions), not second person. Use objective, instructional language (e.g., "To accomplish X, do Y" rather than "You should do X" or "If you need to do X"). This maintains consistency and clarity for AI consumption. Avoid ALL CAPS for emphasis — use bold markdown or section headings instead. Avoid CRITICAL/MANDATORY/MUST qualifiers; direct imperatives are sufficient for Claude 4.6.
To complete SKILL.md, answer the following questions:
What is the purpose of the skill, in a few sentences?
When should the skill be used?
In practice, how should Claude use the skill? All reusable skill contents developed above should be referenced so that Claude knows how to use them.
Claude 4.6 Prompting Alignment
When writing or reviewing skill instructions, follow these patterns:
Language calibration:
Use direct imperatives without ALL CAPS emphasis. "Use Firecrawl for web scraping" not "ALWAYS use Firecrawl" or "You MUST use Firecrawl."
Replace CRITICAL/MANDATORY/MUST markers with plain headings. Claude 4.6 follows well-structured instructions without coercive framing.
Explain WHY behind directives. "Use --only-main-content to reduce token consumption" not "ALWAYS use --only-main-content." Claude generalizes better from explanations.
Remove anti-laziness prompts:
Do not include "be thorough," "think carefully," "do not be lazy," or motivational framing. Claude 4.6 is already proactive — these amplify it into over-planning or write-then-rewrite loops.
Subagent guidance (for orchestration skills):
Include explicit guidance on when NOT to spawn agents. Claude 4.6 tends to reach for subagents even when a direct approach is faster.
"Use agents when tasks can run in parallel or require isolated context. For sequential tasks, single-file edits, or work completable in under 5 minutes, work directly."
Overeagerness prevention:
Include guidance about minimal solutions. Factual quality criteria ("maintain existing conventions") outperform motivational framing ("fight entropy").
Step 5: Packaging a Skill
Once the skill is ready, it should be packaged into a distributable zip file that gets shared with the user. The packaging process automatically validates the skill first to ensure it meets all requirements:
Package the skill if validation passes, creating a zip file named after the skill (e.g., my-skill.zip) that includes all files and maintains the proper directory structure for distribution.
If validation fails, the script will report the errors and exit without creating a package. Fix any validation errors and run the packaging command again.
Step 6: Iterate
After testing the skill, users may request improvements. Often this happens right after using the skill, with fresh context of how the skill performed.
Iteration workflow:
Use the skill on real tasks
Notice struggles or inefficiencies
Identify how SKILL.md or bundled resources should be updated
Implement changes and test again
Sharing Skills
Skills can be distributed at different scopes:
Project skills: Commit .claude/skills/ to version control
Plugins: Create a skills/ directory in your plugin
Check the description includes keywords users would naturally say
Verify the skill appears in response to "What skills are available?"
Try rephrasing the request to match the description more closely
Invoke it directly with /skill-name if the skill is user-invocable
Skill triggers too often
If Claude uses a skill when not wanted:
Make the description more specific
Add disable-model-invocation: true if only manual invocation is wanted
Claude doesn't see all skills
Skill descriptions are loaded into context. If there are many skills, they may exceed the character budget (default 15,000 characters). Run /context to check for a warning about excluded skills.
To increase the limit, set the SLASH_COMMAND_TOOL_CHAR_BUDGET environment variable.
