# Skill Creator > Guide for creating effective skills that extend agent capabilities with specialized knowledge, workflows, or tool integrations. Use this skill when the user asks to: (1) create a new skill, (2) make a skill, (3) build a skill, (4) set up a skill, (5) initialize a skill, (6) scaffold a skill, (7) update or modify an existing skill, (8) validate a skill, (9) learn about skill structure, (10) unders… - **Type:** Skill - **Install:** `agentstack add skill-markdevshop-ag3nt-skill-creator` - **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior - **Seller:** [markdevshop](https://agentstack.voostack.com/s/markdevshop) - **Installs:** 0 - **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills) - **Latest version:** 0.1.0 - **License:** MIT - **Upstream author:** [markdevshop](https://github.com/markdevshop) - **Source:** https://github.com/markdevshop/AG3NT/tree/main/vendor/deepagents/libs/deepagents-cli/examples/skills/skill-creator ## Install ```sh agentstack add skill-markdevshop-ag3nt-skill-creator ``` Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent. ## About # Skill Creator This skill provides guidance for creating effective skills. ## About Skills Skills are modular, self-contained packages that extend agent capabilities by providing specialized knowledge, workflows, and tools. Think of them as "onboarding guides" for specific domains or tasks—they transform a general-purpose agent into a specialized agent equipped with procedural knowledge and domain expertise. ### Skill Location for Deepagents In deepagents CLI, skills are stored in `~/.deepagents//skills/` where `` is your agent configuration name (default is `agent`). For example, with the default configuration, skills live at: ``` ~/.deepagents/agent/skills/ ├── skill-name-1/ │ └── SKILL.md ├── skill-name-2/ │ └── SKILL.md └── ... ``` ### What Skills Provide 1. Specialized workflows - Multi-step procedures for specific domains 2. Tool integrations - Instructions for working with specific file formats or APIs 3. Domain expertise - Company-specific knowledge, schemas, business logic 4. Bundled resources - Scripts, references, and assets for complex and repetitive tasks ## Core Principles ### Concise is Key The context window is a public good. Skills share the context window with everything else the agent needs: system prompt, conversation history, other Skills' metadata, and the actual user request. **Default assumption: The agent is already very capable.** Only add context the agent doesn't already have. Challenge each piece of information: "Does the agent really need this explanation?" and "Does this paragraph justify its token cost?" Prefer concise examples over verbose explanations. ### Set Appropriate Degrees of Freedom Match the level of specificity to the task's fragility and variability: **High freedom (text-based instructions)**: Use when multiple approaches are valid, decisions depend on context, or heuristics guide the approach. **Medium freedom (pseudocode or scripts with parameters)**: Use when a preferred pattern exists, some variation is acceptable, or configuration affects behavior. **Low freedom (specific scripts, few parameters)**: Use when operations are fragile and error-prone, consistency is critical, or a specific sequence must be followed. Think of the agent as exploring a path: a narrow bridge with cliffs needs specific guardrails (low freedom), while an open field allows many routes (high freedom). ### Anatomy of a Skill Every skill consists of a required SKILL.md file and optional bundled resources: ``` skill-name/ ├── SKILL.md (required) │ ├── YAML frontmatter metadata (required) │ │ ├── name: (required) │ │ └── description: (required) │ └── Markdown instructions (required) └── Bundled Resources (optional) ├── scripts/ - Executable code (Python/Bash/etc.) ├── references/ - Documentation intended to be loaded into context as needed └── assets/ - Files used in output (templates, icons, fonts, etc.) ``` #### SKILL.md (required) Every SKILL.md consists of: - **Frontmatter** (YAML): Contains `name` and `description` fields. These are the only fields that the agent reads to determine when the skill gets used, thus it is very important to be clear and comprehensive in describing what the skill is, and when it should be used. - **Body** (Markdown): Instructions and guidance for using the skill. Only loaded AFTER the skill triggers (if at all). #### Bundled Resources (optional) ##### Scripts (`scripts/`) 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, may be executed without loading into context - **Note**: Scripts may still need to be read by the agent for patching or environment-specific adjustments ##### References (`references/`) Documentation and reference material intended to be loaded as needed into context to inform the agent's process and thinking. - **When to include**: For documentation that the agent 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 the agent determines it's needed - **Best practice**: If files are large (>10k words), include 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/`) Files not intended to be loaded into context, but rather used within the output the agent 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 the agent to use files without loading them into context #### What to Not Include in a Skill A skill should only contain essential files that directly support its functionality. Do NOT create extraneous documentation or auxiliary files, including: - README.md - INSTALLATION_GUIDE.md - QUICK_REFERENCE.md - CHANGELOG.md - etc. The skill should only contain the information needed for an AI agent to do the job at hand. It should not contain auxilary context about the process that went into creating it, setup and testing procedures, user-facing documentation, etc. Creating additional documentation files just adds clutter and confusion. ### Progressive Disclosure Design Principle Skills use a three-level loading system to manage context efficiently: 1. **Metadata (name + description)** - Always in context (~100 words) 2. **SKILL.md body** - When skill triggers ( --path ``` For deepagents CLI, use the agent's skills directory: ```bash scripts/init_skill.py --path ~/.deepagents/agent/skills ``` The script: - Creates the skill directory at the specified path - 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 an agent to use. Include information that would be beneficial and non-obvious to the agent. Consider what procedural knowledge, domain-specific details, or reusable assets would help the agent execute these tasks more effectively. #### Learn Proven Design Patterns Consult these helpful guides based on your skill's needs: - **Multi-step processes**: See references/workflows.md for sequential workflows and conditional logic - **Specific output formats or quality standards**: See references/output-patterns.md for template and example patterns These files contain established best practices for effective skill design. #### 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/`. Added scripts must be tested by actually running them to ensure there are no bugs and that the output matches what is expected. If there are many similar scripts, only a representative sample needs to be tested to ensure confidence that they all work while balancing time to completion. Any example files and directories not needed for the skill should be deleted. The initialization script creates example files in `scripts/`, `references/`, and `assets/` to demonstrate structure, but most skills won't need all of them. #### Update SKILL.md **Writing Guidelines:** Always use imperative/infinitive form. ##### Frontmatter Write the YAML frontmatter with `name` and `description`: - `name`: The skill name - `description`: This is the primary triggering mechanism for your skill, and helps the agent understand when to use the skill. - Include both what the Skill does and specific triggers/contexts for when to use it. - Include all "when to use" information here - Not in the body. The body is only loaded after triggering, so "When to Use This Skill" sections in the body are not helpful to the agent. - Example description for a `docx` skill: "Comprehensive document creation, editing, and analysis with support for tracked changes, comments, formatting preservation, and text extraction. Use when working with professional documents (.docx files) for: (1) Creating new documents, (2) Modifying or editing content, (3) Working with tracked changes, (4) Adding comments, or any other document tasks" Do not include any other fields in YAML frontmatter. ##### Body Write instructions for using the skill and its bundled resources. ### Step 5: Validate the Skill Once development of the skill is complete, validate it to ensure it meets all requirements: ```bash scripts/quick_validate.py ``` The validation script checks: - YAML frontmatter format and required fields - Skill naming conventions (hyphen-case, max 64 characters) - Description completeness (no angle brackets, max 1024 characters) - Required fields: `name` and `description` - Allowed frontmatter properties only: `name`, `description`, `license`, `allowed-tools`, `metadata` If validation fails, fix the reported errors and run the validation 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:** 1. Use the skill on real tasks 2. Notice struggles or inefficiencies 3. Identify how SKILL.md or bundled resources should be updated 4. Implement changes and test again ## Source & license This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code. - **Author:** [markdevshop](https://github.com/markdevshop) - **Source:** [markdevshop/AG3NT](https://github.com/markdevshop/AG3NT) - **License:** MIT Install and usage instructions live in the source repository linked above. ## Pricing - **Free** — Free ## Security capabilities Automated source analysis of v0.1.0 — what this tool can access: - **Network access:** no - **Filesystem access:** no - **Shell / process execution:** no - **Environment & secrets:** no - **Dynamic code execution:** no *"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.* ## Versions - **0.1.0** — security scan: passed — Imported from the upstream source. ## Links - Listing page: https://agentstack.voostack.com/l/skill-markdevshop-ag3nt-skill-creator - Seller: https://agentstack.voostack.com/s/markdevshop - Browse the marketplace: https://agentstack.voostack.com/browse --- Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.