Agent Skill Builder

Build Claude or Codex SKILL.md files from Markdown drafts in your browser.

Skill Builder Workbench
Generated SKILL.md
Frontmatter ready Body ready
What is a SKILL.md file?

An Agent Skill is a folder holding a SKILL.md file that teaches a coding agent how to handle one kind of task. The file opens with YAML frontmatter carrying a name and a description, followed by Markdown instructions. The agent reads the description to decide when the skill applies, so that one line decides whether the skill is ever used.

How the builder works

Paste or write a Markdown draft and the builder rewrites it into a valid skill file inside this browser tab. Frontmatter already present in the draft is removed before the new block is written, line endings and repeated blank lines are normalized, and the first H1 becomes the display title when the draft has one. What comes out is deterministic YAML frontmatter followed by a title plus When to Use and Instructions sections.

Common Use Cases
  • Drafting a new Claude or Codex skill from rough Markdown notes
  • Cleaning existing frontmatter before saving a SKILL.md file
  • Preparing a browser-local skill handoff without calling an AI API
  • Turning a runbook or incident checklist into a skill the agent can pick up on its own
  • Rewriting a skill that the agent never triggers, so the description names the situation instead of the task
What the builder guarantees
  • Deterministic YAML frontmatter with the name and description an agent matches on
  • Existing frontmatter stripped before the new block is added
  • Normalized line endings and collapsed repeated blank lines
  • A title plus When to Use and Instructions sections in every generated file
  • Cleanup that runs entirely in this browser tab, with no external AI API call
Examples
Input: # Quick Triage Helper
Output: name: quick-triage-helper
Input: --- title: old ---
Output: Old frontmatter removed, new name and description written
Input: ~/.claude/skills/quick-triage-helper/SKILL.md
Output: Where to save the generated file for a personal skill
Frequently Asked Questions

Where does the generated file go?

Save it as SKILL.md inside a folder named after the skill: ~/.claude/skills/<name>/SKILL.md for a personal skill, or .claude/skills/<name>/SKILL.md inside a project so the whole repository shares it.

What makes a description good enough for the agent to pick the skill?

Name the situation that should trigger it, not the feature. A description that starts with when to use it beats one that only restates the title, because the agent matches the description against the task in front of it.

Does my draft leave the browser?

No. The cleanup and frontmatter generation run in this tab, and no AI API is called. Nothing is uploaded unless you copy the output somewhere yourself.

Does the output work with agents other than Claude?

The result is plain Markdown with YAML frontmatter, so any agent that loads skill files from a folder can read it. Only the install path differs between tools.

Can I keep editing after generating?

Yes. The output is a starting point. Edit the Instructions section freely, and run the draft through the builder again whenever the frontmatter needs to be rewritten.