This reference documents common patterns for skill authoring, including templates, examples, terminology consistency, and anti-patterns. All patterns use pure XML structure.
Provide templates for output format. Match the level of strictness to your needs.
Use when output format must be exact and consistent:
```xml
ALWAYS use this exact template structure:
```markdown
# [Analysis Title]
## Executive summary
[One-paragraph overview of key findings]
## Key findings
- Finding 1 with supporting data
- Finding 2 with supporting data
- Finding 3 with supporting data
## Recommendations
1. Specific actionable recommendation
2. Specific actionable recommendation
```
```
**When to use**: Compliance reports, standardized formats, automated processing
Use when Claude should adapt the format based on context:
```xml
Here is a sensible default format, but use your best judgment:
```markdown
# [Analysis Title]
## Executive summary
[Overview]
## Key findings
[Adapt sections based on what you discover]
## Recommendations
[Tailor to the specific context]
```
Adjust sections as needed for the specific analysis type.
```
**When to use**: Exploratory analysis, context-dependent formatting, creative tasks
For skills where output quality depends on seeing examples, provide input/output pairs.
```xml
Generate commit messages following conventional commit format.
Generate commit messages following these examples:
Added user authentication with JWT tokens
Fixed bug where dates displayed incorrectly in reports
Follow this style: type(scope): brief description, then detailed explanation.
```
- Output format has nuances that text explanations can't capture
- Pattern recognition is easier than rule following
- Examples demonstrate edge cases
- Multi-shot learning improves quality
Choose one term and use it throughout the skill. Inconsistent terminology confuses Claude and reduces execution quality.
Consistent usage:
- Always "API endpoint" (not mixing with "URL", "API route", "path")
- Always "field" (not mixing with "box", "element", "control")
- Always "extract" (not mixing with "pull", "get", "retrieve")
```xml
Extract data from API endpoints using field mappings.
1. Identify the API endpoint
2. Map response fields to your schema
3. Extract field values
```
Inconsistent usage creates confusion:
```xml
Pull data from API routes using element mappings.
1. Identify the URL
2. Map response boxes to your schema
3. Retrieve control values
```
Claude must now interpret: Are "API routes" and "URLs" the same? Are "fields", "boxes", "elements", and "controls" the same?
1. Choose terminology early in skill development
2. Document key terms in `` or ``
3. Use find/replace to enforce consistency
4. Review reference files for consistent usage
Provide a default approach with an escape hatch for special cases, not a list of alternatives. Too many options paralyze decision-making.
Clear default with escape hatch:
```xml
Use pdfplumber for text extraction:
```python
import pdfplumber
with pdfplumber.open("file.pdf") as pdf:
text = pdf.pages[0].extract_text()
```
For scanned PDFs requiring OCR, use pdf2image with pytesseract instead.
```
Too many options creates decision paralysis:
```xml
You can use any of these libraries:
- **pypdf**: Good for basic extraction
- **pdfplumber**: Better for tables
- **PyMuPDF**: Faster but more complex
- **pdf2image**: For scanned documents
- **pdfminer**: Low-level control
- **tabula-py**: Table-focused
Choose based on your needs.
```
Claude must now research and compare all options before starting. This wastes tokens and time.
1. Recommend ONE default approach
2. Explain when to use the default (implied: most of the time)
3. Add ONE escape hatch for edge cases
4. Link to advanced reference if multiple alternatives truly needed
Common mistakes to avoid when authoring skills.
❌ **BAD**: Using markdown headings in skill body:
```markdown
# PDF Processing
## Quick start
Extract text with pdfplumber...
## Advanced features
Form filling requires additional setup...
```
✅ **GOOD**: Using pure XML structure:
```xml
PDF processing with text extraction, form filling, and merging capabilities.
Extract text with pdfplumber...
Form filling requires additional setup...
```
**Why it matters**: XML provides semantic meaning, reliable parsing, and token efficiency.
❌ **BAD**:
```yaml
description: Helps with documents
```
✅ **GOOD**:
```yaml
description: Extract text and tables from PDF files, fill forms, merge documents. Use when working with PDF files or when the user mentions PDFs, forms, or document extraction.
```
**Why it matters**: Vague descriptions prevent Claude from discovering and using the skill appropriately.
❌ **BAD**:
```yaml
description: I can help you process Excel files and generate reports
```
✅ **GOOD**:
```yaml
description: Processes Excel files and generates reports. Use when analyzing spreadsheets or .xlsx files.
```
**Why it matters**: Skills must use third person. First/second person breaks the skill metadata pattern.
❌ **BAD**: Directory name doesn't match skill name or verb-noun convention:
- Directory: `facebook-ads`, Name: `facebook-ads-manager`
- Directory: `stripe-integration`, Name: `stripe`
- Directory: `helper-scripts`, Name: `helper`
✅ **GOOD**: Consistent verb-noun convention:
- Directory: `manage-facebook-ads`, Name: `manage-facebook-ads`
- Directory: `setup-stripe-payments`, Name: `setup-stripe-payments`
- Directory: `process-pdfs`, Name: `process-pdfs`
**Why it matters**: Consistency in naming makes skills discoverable and predictable.
❌ **BAD**:
```xml
You can use pypdf, or pdfplumber, or PyMuPDF, or pdf2image, or pdfminer, or tabula-py...
```
✅ **GOOD**:
```xml
Use pdfplumber for text extraction:
```python
import pdfplumber
```
For scanned PDFs requiring OCR, use pdf2image with pytesseract instead.
```
**Why it matters**: Decision paralysis. Provide one default approach with escape hatch for special cases.
❌ **BAD**: References nested multiple levels:
```
SKILL.md → advanced.md → details.md → examples.md
```
✅ **GOOD**: References one level deep from SKILL.md:
```
SKILL.md → advanced.md
SKILL.md → details.md
SKILL.md → examples.md
```
**Why it matters**: Claude may only partially read deeply nested files. Keep references one level deep from SKILL.md.
❌ **BAD**:
```xml
See scripts\validate.py for validation
```
✅ **GOOD**:
```xml
See scripts/validate.py for validation
```
**Why it matters**: Always use forward slashes for cross-platform compatibility.
**Problem**: When showing examples of dynamic context syntax (exclamation mark + backticks) or file references (@ prefix), the skill loader executes these during skill loading.
❌ **BAD** - These execute during skill load:
```xml
Load current status with: !`git status`
Review dependencies in: @package.json
```
✅ **GOOD** - Add space to prevent execution:
```xml
Load current status with: ! `git status` (remove space before backtick in actual usage)
Review dependencies in: @ package.json (remove space after @ in actual usage)
```
**When this applies**:
- Skills that teach users about dynamic context (slash commands, prompts)
- Any documentation showing the exclamation mark prefix syntax or @ file references
- Skills with example commands or file paths that shouldn't execute during loading
**Why it matters**: Without the space, these execute during skill load, causing errors or unwanted file reads.
❌ **BAD**: Missing required tags:
```xml
Use this tool for processing...
```
✅ **GOOD**: All required tags present:
```xml
Process data files with validation and transformation.
Use this tool for processing...
- Input file successfully processed
- Output file validates without errors
- Transformation applied correctly
```
**Why it matters**: Every skill must have ``, ``, and `` (or ``).
❌ **BAD**: Mixing XML tags with markdown headings:
```markdown
PDF processing capabilities
## Quick start
Extract text with pdfplumber...
## Advanced features
Form filling...
```
✅ **GOOD**: Pure XML throughout:
```xml
PDF processing capabilities
Extract text with pdfplumber...
Form filling...
```
**Why it matters**: Consistency in structure. Either use pure XML or pure markdown (prefer XML).
❌ **BAD**: Forgetting to close XML tags:
```xml
Process PDF files
Use pdfplumber...
```
✅ **GOOD**: Properly closed tags:
```xml
Process PDF files
Use pdfplumber...
```
**Why it matters**: Unclosed tags break XML parsing and create ambiguous boundaries.
Keep SKILL.md concise by linking to detailed reference files. Claude loads reference files only when needed.
```xml
Manage Facebook Ads campaigns, ad sets, and ads via the Marketing API.
See [basic-operations.md](basic-operations.md) for campaign creation and management.
**Custom audiences**: See [audiences.md](audiences.md)
**Conversion tracking**: See [conversions.md](conversions.md)
**Budget optimization**: See [budgets.md](budgets.md)
**API reference**: See [api-reference.md](api-reference.md)
```
**Benefits**:
- SKILL.md stays under 500 lines
- Claude only reads relevant reference files
- Token usage scales with task complexity
- Easier to maintain and update
For skills with validation steps, make validation scripts verbose and specific.
```xml
After making changes, validate immediately:
```bash
python scripts/validate.py output_dir/
```
If validation fails, fix errors before continuing. Validation errors include:
- **Field not found**: "Field 'signature_date' not found. Available fields: customer_name, order_total, signature_date_signed"
- **Type mismatch**: "Field 'order_total' expects number, got string"
- **Missing required field**: "Required field 'customer_name' is missing"
Only proceed when validation passes with zero errors.
```
**Why verbose errors help**:
- Claude can fix issues without guessing
- Specific error messages reduce iteration cycles
- Available options shown in error messages
For complex multi-step workflows, provide a checklist Claude can copy and track progress.
```xml
Copy this checklist and check off items as you complete them:
```
Task Progress:
- [ ] Step 1: Analyze the form (run analyze_form.py)
- [ ] Step 2: Create field mapping (edit fields.json)
- [ ] Step 3: Validate mapping (run validate_fields.py)
- [ ] Step 4: Fill the form (run fill_form.py)
- [ ] Step 5: Verify output (run verify_output.py)
```
**Analyze the form**
Run: `python scripts/analyze_form.py input.pdf`
This extracts form fields and their locations, saving to `fields.json`.
**Create field mapping**
Edit `fields.json` to add values for each field.
**Validate mapping**
Run: `python scripts/validate_fields.py fields.json`
Fix any validation errors before continuing.
**Fill the form**
Run: `python scripts/fill_form.py input.pdf fields.json output.pdf`
**Verify output**
Run: `python scripts/verify_output.py output.pdf`
If verification fails, return to Step 2.
```
**Benefits**:
- Clear progress tracking
- Prevents skipping steps
- Easy to resume after interruption