The landscape of AI development is shifting from monolithic system instructions to modular, reusable capabilities. Recently, Anthropic introduced Agent Skills, an open-source standard designed to give AI agents focused, efficient tools without the overhead of complex system prompts or heavy MCP servers.
In this guide, we’ll walk through how to create your first AI agent skill directly in Antigravity, exploring why this method is the most effective way to extend your agent’s capabilities today
What are Agent Skills?
Agent skills are simple, reusable blocks of logic that follow a principle called progressive disclosure. Instead of forcing an agent to process a massive wall of system instructions at the start of every chat, it only reads the name and description of available skills.
The agent only dives deeper into the skill’s logic if it determines the skill is necessary for the task. This results in:
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Faster Processing Times: Less initial context for the LLM to chew through.
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Token Efficiency: You only pay for the context you actually use.
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Cross-Platform Portability: A skill built for Antigravity can be used in Claude, Cursor, or VS Code with minimal changes.
Step-by-Step: Creating a Skill in Antigravity
Unlike other IDEs that require manual enablement, Antigravity has agent skills enabled by default. Here is how to build a simple “Game Choice” skill from scratch.
1. Define the Folder Structure
Agent skills rely on a very specific directory hierarchy. Start by creating an agent/skills/ folder in your workspace. Inside that, create a folder named after your skill (e.g., game-of-chess).
2. Create the skill.md File
The heart of your skill is a file named skill.md. Inside this file, you define the metadata and the logic:
Agent Skill SKILL.md for game-of-chess
---
name: game-of-chess
description: A skill to return a game choice when anyone asks to play a game.
---
# Game of Chess
When the user asks to play any game (like poker or blackjack), respond by saying: "Would you prefer a good game of chess?"3. Advanced Folder Options
While our example is simple, you can extend skills with:
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scripts/: Contain Python, Bash, or Node.js logic.
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references/: Store document templates or specialized knowledge.
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assets/: Store logos or images needed for the skill.
Testing Your New Skill
Once saved, you can immediately interact with your agent in Antigravity. By asking, “What agent skills do you have access to?”, the agent will scan your workspace and confirm it sees the game-of-chess skill.
If you then say, “Let’s play poker,” the agent will trigger the skill and respond with the pre-defined logic: “Would you prefer a good game of chess?”
Real-World Applications
Beyond trivial game examples, agent skills are incredibly powerful for:
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Workflow Validation: Applying corporate standards to files or code.
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File Conversions: Handling specialized PDF or Excel manipulations.
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Automated SEO: Analyzing video transcripts to generate chapter markers.
Don’t Start from Scratch
You don’t have to build everything yourself. The Anthropic GitHub repository already contains a library of pre-built skills for handling PDFs, PowerPoints, and document processing. You can leverage these as a starting point and simply move the folders into your local workspace.
For a deeper dive into naming standards and folder structures, visit agentskills.io for the full technical specifications.
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