What are Agent Skills?
Agent Skills are folders of instructions, prompts, examples, and resources that an LLM can load when relevant to perform specialized tasks consistently. Instead of putting everything in the system prompt, skills let you modularize expertise.
"Skills are like apps for your agent—install them once, use them whenever needed."
Just as you install apps on your phone for specific functions, skills give agents specialized capabilities without bloating every conversation.
How Agent Skills Work
Skill Discovery
The host initially exposes names and descriptions. The model can choose a relevant skill, or the user invokes one explicitly. Keyword rules are an optional host implementation, not part of the skill format.
Skill Loading
The relevant skill's instructions, examples, and context are loaded into the agent's working memory. This adds specialized knowledge without polluting the base system prompt.
Skill Execution
The agent follows the skill's instructions to complete the task, using any provided templates, checklists, or scripts. Results are returned to the user.
Interactive Skill Demo
Inspect a local selection rule, standard metadata and progressive loading.
Select a skill, then load its instructions
This local teaching matcher uses the displayed whole-word rules in English and German. It is not an Agent Skills standard or a model-confidence estimate. Real hosts commonly let the model select from skill descriptions.
Initially available: name and description
--- name: code-review description: "Performs thorough code reviews following team standards" ---
Skill Structure
Anatomy of a skill folder
SKILL.md is the entry point. Standard required frontmatter fields are name and description; the Markdown body contains the instructions. Load supporting files only when needed.
Types of Agent Skills
Domain Skills
Domain-specific references and procedures. They can support specialized work but do not replace domain expertise or evidence checks.
Workflow Skills
Multi-step processes with defined stages—code review workflows, content publishing pipelines, incident response procedures.
Format Skills
Consistent output formatting—API documentation, changelog entries, meeting summaries. Ensure outputs match your standards.
Integration Skills
Instructions for working with specific tools or services—GitHub workflows, Jira ticket creation, Slack notifications.
Skills vs. Tools
Tools
- •Execute actions (read files, call APIs, run code)
- •Defined by function signatures and schemas
- •The "hands" of the agent
Skills
- •Provide knowledge and methodology (how to approach tasks)
- •Defined by instructions and examples
- •The "expertise" of the agent
Skills and tools work together: a code review skill tells the agent what to look for, while tools let it read the code and leave comments.
Benefits of Skills
Specialization Without Bloat
Keep the base system prompt lean. Load specialized knowledge only when needed, preserving context window for the actual task.
Consistency
Make the intended procedure reviewable and repeatable. Verify whether the agent follows it; written instructions alone do not guarantee consistent execution.
Shareability
Skills are just folders—share them across projects, teams, or publicly. Build once, use everywhere.
Iteration
Improve skills independently of the agent. Update the code review skill without touching the rest of your agent setup.
Example: Code Review Skill
--- name: code-reviewer description: Performs thorough code reviews following team standards --- # Example: Code Review Skill When reviewing code, analyze for correctness, performance, security, and maintainability. ## Test - [ ] Check for common security vulnerabilities - [ ] Verify error handling is comprehensive - [ ] Look for performance anti-patterns - [ ] Ensure code follows style guidelines
Best Practices
Keep Skills Focused
One skill, one purpose. If a skill is doing too many things, split it up. Focused skills are easier to maintain and compose.
Include Examples
Show, don't just tell. Include input/output examples that demonstrate exactly what good execution looks like.
Version Your Skills
Track changes to skills over time. When behavior changes unexpectedly, you can trace it back to a skill update.
Key Takeaways
- 1Skills are reusable instruction packages that give agents specialized expertise on demand
- 2Unlike tools (which execute actions), skills provide knowledge and methodology
- 3Well-designed skills improve consistency and reduce system prompt bloat
- 4The skill framework enables modular agent development—build once, share everywhere