Skills are essentially reusable prompt templates that encode project-specific knowledge. Instead of explaining “use Bun APIs, not Node fs” every time, you write it once in a skill. The LLM automatically loads it when relevant.

OpenCode intentionally supports Claude Code’s .claude/skills/ directory structure, so skills written for Claude Code work in OpenCode too. This is controlled by the OPENCODE_DISABLE_CLAUDE_CODE_SKILLS flag.

It’s stored at

│ Skill Definition │ C:\Users\ncarucci\Documents\gitfolder\opencode\packages\opencode\src\skill\skill.ts │
├──────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────┤
│ Skill Tool │ C:\Users\ncarucci\Documents\gitfolder\opencode\packages\opencode\src\tool\skill.ts │
├──────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────┤
│ Skill Debug CLI │ C:\Users\ncarucci\Documents\gitfolder\opencode\packages\opencode\src\cli\cmd\debug\skill.ts │
├──────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────┤
│ Skill Tests │ C:\Users\ncarucci\Documents\gitfolder\opencode\packages\opencode\test\skill\skill.test.ts

Here is real skill use example: bun-file-io

 name: bun-file-io
  description: Use this when you are working on file operations like reading,
               writing, scanning, or deleting files. It summarizes the preferred
               file APIs and patterns used in this repo.
  ---

  ## Use this when
  - Editing file I/O or scans in `packages/opencode`
  - Handling directory operations or external tools

  ## Bun file APIs (from Bun docs)
  - `Bun.file(path)` is lazy; call `text`, `json`, `stream`...
  - `Bun.write(dest, input)` writes strings, buffers, Blobs...
  - `Bun.Glob` + `Array.fromAsync(glob.scan({...}))` for scans
  ...

If a user asks a question: “Help me add a function to read a config file”, LLM sees available skills. The skill tool description includes:

 <available_skills>
    <skill>
      <name>bun-file-io</name>
      <description>Use this when you are working on file operations like
      reading, writing, scanning, or deleting files...</description>
    </skill>
  </available_skills>

So this skill is loaded and injected into context

the LLM follow the guidance from this skill and knows how to use Bun API instead of Node.js fs.

So if i want to store more still, create a folder, and create SKILL.md

---

name: my-skill
description: Use this when deploying to AWS. Contains deployment patterns and commands.

---

## Prerequisites

• AWS CLI configured
• Valid credentials in ~/.aws Deployment Steps

1. Build the project: npm run build
2. Deploy: aws s3 sync ./dist s3://my-bucket
3. Invalidate cache: aws cloudfront create-invalidation ... Rollback If deployment fails:
   “`bash
   aws s3 sync s3://my-bucket-backup s3://my-bucket