skill-creator

Skill Creator Guide

This guide helps you create effective skills for Apollo GraphQL and GraphQL development following the Agent Skills specification.

What is a Skill?

A skill is a directory containing instructions that extend an AI agent's capabilities with specialized knowledge, workflows, or tool integrations. Skills activate automatically when agents detect relevant tasks.

Directory Structure

A skill requires at minimum a SKILL.md file:

skill-name/
├── SKILL.md              # Required - main instructions
├── references/           # Optional - detailed documentation
│   ├── topic-a.md
│   └── topic-b.md
├── scripts/              # Optional - executable helpers
│   └── validate.sh
├── templates/            # Optional - config/code templates
│   └── config.yaml
└── assets/               # Optional - static resources (images, schemas, data files)

SKILL.md Format

Frontmatter (Required)

---
name: skill-name
description: >
  A clear description of what this skill does and when to use it.

Frontmatter Fields

Name Rules

• Use lowercase letters, numbers, and hyphens only
• Do not start or end with a hyphen
• Do not use consecutive hyphens (--)
• Must match the parent directory name

Good: apollo-client, graphql-schema, rover Bad: Apollo-Client, -apollo, apollo--client

Description Best Practices

Write descriptions that help agents identify when to activate the skill:

Body Content

The markdown body contains instructions the agent follows. Structure it for clarity:

Recommended Sections

1. Overview - Brief explanation of the skill's purpose
2. Process - Step-by-step workflow (use checkboxes for multi-step processes)
3. Quick Reference - Common patterns and syntax
4. Security - Risks, mitigations, and validation (if the skill touches anything security-sensitive)
5. Reference Files - Links to detailed documentation
6. Key Rules - Important guidelines organized by topic
7. Ground Rules - Critical do's and don'ts

Example Structure

Security-Sensitive Content

When a skill generates configuration, code, or guidance that could cause security issues if misused, the skill MUST make those risks explicit and visible to the LLM. An LLM cannot infer security implications from context alone — it needs clearly labeled signals.

When does a skill need security guidance?

If any of these apply, the skill is security-sensitive:

• Generates config that controls access to data (caching, auth, CORS, permissions)
• Handles secrets, credentials, or tokens
• Produces code that runs with elevated privileges
• Controls what data is shared, public, or exposed to users
• Configures network bindings, endpoints, or external access

How to surface security in a skill

1. Dedicated Security section in SKILL.md or a reference file, labeled ## Security. Not "Private data" or "Customization" — use the word "Security" so the LLM recognizes the category.

2. Explicit warnings at the point of risk — place security guidance next to the config or code that creates the risk, not in a separate file the LLM may not load:

   ### Response caching scope
    
   > **Security: data leakage risk.** All cached data is PUBLIC by default.
   > User-specific fields MUST use `scope: PRIVATE` with a `private_id`
   > configured, or they will be shared across all users.

3. Validation checklist items — every security-sensitive feature must have corresponding checks in the validation checklist. Group them under a ## Security heading.

4. Ground rules — add ALWAYS/NEVER rules for security-critical behavior. These are the strongest signal to the LLM.

5. Require the data model — if correct security configuration depends on understanding the user's data model (e.g., which fields are user-specific), the skill must instruct the LLM to ask the user before generating config. Do not let the LLM guess.

Anti-patterns

• Describing a security-sensitive default (like "public by default") without labeling it as a security concern
• Placing security guidance only in reference files that load on demand — the SKILL.md itself must contain the key warnings
• Using soft language ("you may want to consider") for hard security requirements — use "MUST" and "NEVER"
• Assuming the LLM understands which fields in a schema are private — require explicit user input

Progressive Disclosure

Structure skills to minimize context usage:

1. Metadata (~100 tokens): name and description load at startup for all skills
2. Instructions (< 5000 tokens): Full SKILL.md loads when skill activates
3. References (as needed): Files in references/ load only when required

Keep SKILL.md under 500 lines. Move detailed documentation to reference files.

Reference Files

Use references/ for detailed documentation:

references/
├── setup.md          # Installation and configuration
├── patterns.md       # Common patterns and examples
├── troubleshooting.md # Error solutions
└── api.md            # API reference

Reference files should be:

• Focused on a single topic
• Self-contained (readable without other files)
• Under 300 lines each

Link to references from SKILL.md:

## Reference Files
 
- [Setup](references/setup.md) - Installation and configuration
- [Patterns](references/patterns.md) - Common patterns and examples

Scripts

Use scripts/ for executable helpers agents can run:

scripts/
├── validate.sh       # Validation commands
├── setup.py          # Setup automation
└── check-version.sh  # Version checking

Scripts should be self-contained, include error handling, and have a usage comment at the top. Pre-approve them in allowed-tools (e.g., Bash(./scripts/validate.sh:*)).

Templates

Use templates/ for config files, boilerplate, or starter code:

templates/
├── config.yaml       # Default configuration
├── config-v2.yaml    # Version-specific variant
└── example-app/      # Starter project

Templates are copied or adapted by the agent — not executed directly.

Writing Style

Follow the Apollo Voice for all skill content:

Tone

• Approachable and helpful
• Opinionated and authoritative (prescribe the "happy path")
• Direct and action-oriented

Language

• Use American English
• Keep language simple; avoid idioms
• Use present tense and active voice
• Use imperative verbs for instructions

Formatting

• Use sentence casing for headings
• Use code font for symbols, commands, file paths, and URLs
• Use bold for UI elements users click
• Use hyphens (-) for unordered lists

Avoid

• "Simply", "just", "easy" (can be condescending)
• Vague phrases like "click here"
• Semicolons (use periods instead)
• "We" unless clearly referring to Apollo

Reference Files

For Apollo GraphQL-specific guidance:

• Apollo Skills - Patterns and examples for Apollo GraphQL skills

Versioning

Use semantic versioning ("X.Y.Z") for the version field in metadata:

metadata:
  author: apollographql
  version: "1.0.0"

• Major (X): Breaking changes that alter how the skill behaves or activates (e.g., renamed triggers, removed sections, changed ground rules)
• Minor (Y): New content or capabilities that are backward-compatible (e.g., added reference files, new sections, expanded examples)
• Patch (Z): Small fixes that don't change behavior (e.g., typo corrections, wording tweaks, formatting fixes)

Start new skills at "1.0.0".

Checklist for New Skills

Before publishing a skill, verify:

• name matches directory name and follows naming rules
• description clearly states what the skill does and when to use it
• SKILL.md is under 500 lines
• Reference files are focused and under 300 lines each
• Instructions are clear and actionable
• Code examples are correct and tested
• Ground rules use ALWAYS/NEVER/PREFER format
• Content follows Apollo Voice guidelines

Ground Rules

• ALWAYS include trigger conditions in the description (use numbered list)
• ALWAYS use checkboxes for multi-step processes
• ALWAYS link to reference files for detailed documentation
• NEVER exceed 500 lines in SKILL.md
• NEVER use vague descriptions that don't help agents identify when to activate
• PREFER specific examples over abstract explanations
• PREFER opinionated guidance over listing multiple options
• USE allowed-tools to pre-approve tools the skill needs
• NEVER include Bash(curl:*) in allowed-tools as it grants unrestricted network access and enables curl | sh remote code execution patterns
• ALWAYS include a ## Security section when the skill generates config or code that controls access, caching, auth, secrets, or data exposure
• NEVER bury security-critical guidance only in reference files — the key warnings must appear in SKILL.md where the LLM will always see them
• ALWAYS instruct the LLM to ask the user about their data model before generating security-sensitive config (e.g., which fields are user-specific, which data is public)
• USE explicit blockquote warnings (> **Security: ...**) next to config or code that creates security risks
• ALWAYS add validation checklist items for every security-sensitive feature, grouped under a ## Security heading