Guide · Agent skill
How to use the Skill Creator agent skill (skill-creator)
Updated · written with AI from the project's own documentation and checked against our catalogue data
Skill Creator is an agent skill from the GBrain project that teaches an AI agent how to write a new skill for that repository. A skill is a folder containing a SKILL.md instruction file that tells an agent how to handle a particular kind of task. This guide explains what the skill does, how to install it, how to trigger it, and what it needs, so you can add a new skill in the standard GBrain format.
Skill Creatorgarrytan/gbrain · MIT Download the skill Quick start
- 1Download and unzip. Download the skill ZIP from this page and unzip it to get SKILL.md.
- 2Place the skill folder. Copy the folder into ~/.claude/skills/ for personal use or into the project's .claude/skills/ folder, or upload the ZIP under Settings → Capabilities → Skills in the Claude apps.
- 3Confirm the repository setup. Make sure you are working in a GBrain repository containing skills/manifest.json, skills/RESOLVER.md and the conformance test file, and that Bun is installed.
- 4Ask for a new skill. Make a request that matches a trigger phrase, such as "create a skill" or "new skill", and describe the capability you need.
- 5Review the MECE check. Check the agent's overlap review against existing skills and extend an existing skill if one already covers the need.
- 6Review the generated files. Inspect the new SKILL.md and the edits to manifest.json and RESOLVER.md before accepting them.
- 7Run the conformance test. Run bun test test/skills-conformance.test.ts and fix any missing sections or frontmatter until it passes.
What does the Skill Creator skill make the agent do?
When the skill is active, the agent follows a fixed process to build a new skill. It first identifies the missing capability, then checks existing skills so the new one does not overlap with them. It writes a new SKILL.md using a standard template and registers the skill in the project's manifest and routing files. Finally, it runs a conformance test to verify the result.
The skill's stated guarantees are that the new skill follows the conformance standard (frontmatter plus required sections), that a MECE check against existing triggers has been done, that skills/manifest.json and skills/RESOLVER.md are updated, and that the skill passes the conformance test.
- Identify the gap: what capability is missing and which user intent has no skill
- MECE check: review skills/manifest.json and skills/RESOLVER.md; extend an existing skill if one already covers the case
- Create SKILL.md from the template with frontmatter, Contract, Phases, Output Format, When it fails and Anti-Patterns sections
- Add the skill to skills/manifest.json and add a routing entry in skills/RESOLVER.md
- Verify with bun test test/skills-conformance.test.ts
Who should use it and what does it need?
This skill is aimed at maintainers of the GBrain repository and developers who keep their own skill library in GBrain's standard format. It only helps write new skills; it does not run existing ones. It is not useful for projects outside GBrain, because the manifest, resolver and conformance test paths are specific to that repository.
It requires the Bun runtime, a GBrain repository containing skills/manifest.json, skills/RESOLVER.md and the conformance test file, and GBrain tools named search and list_pages. The skill does not run scripts and does not use the network.
- Bun runtime, used to run the conformance test
- GBrain repository with skills/manifest.json, skills/RESOLVER.md and test/skills-conformance.test.ts
- GBrain tools named search and list_pages
bun test test/skills-conformance.test.tsInstall Skill Creator in Claude or in a project
Download the skill ZIP from this page and unzip it. The package contains a single file, SKILL.md. Then choose one of the two install locations below.
For a personal install that applies across your projects, place the unzipped skill folder in ~/.claude/skills/. For a single project, place it in that project's .claude/skills/ folder. You can also upload the ZIP in the Claude apps under Settings → Capabilities → Skills.
- Personal: ~/.claude/skills/
- Project only: .claude/skills/ inside the project folder
- Claude apps: Settings → Capabilities → Skills, then upload the ZIP
How do you trigger the skill with a natural request?
The skill is triggered by requests that match its listed phrases. You do not need to name the skill; asking for a new capability in plain words usually works, as long as the wording is close to one of the trigger phrases. Phrases like "create a skill", "new skill" and "improve this skill" are the ones the skill declares.
- "Create a skill that handles weekly meeting summaries."
- "I need a new skill for tagging incoming notes."
- "Improve this skill so it covers edge cases in date parsing."
What does a finished skill look like?
A new skill is a folder under skills/ with a SKILL.md file. The file starts with YAML frontmatter (name, version, description, triggers, tools, mutating) and then contains the sections the conformance test checks for: Contract, Phases, Output Format, When it fails and Anti-Patterns, plus a Tools Used section in the template.
The template is the reference for the structure. Keep the Contract to 3-5 bullet points and the Anti-Patterns to 3-5 items, as the template suggests.
- Frontmatter with name, version, description, triggers, tools and mutating
- Contract, Phases, Output Format, When it fails, Anti-Patterns, Tools Used
---
name: {skill-name}
version: 1.0.0
description: |
{One paragraph describing what the skill does and when to use it.}
triggers:
- "{trigger phrase 1}"
- "{trigger phrase 2}"
tools:
- {tool1}
- {tool2}
mutating: {true|false}
---What to do when the test or resolver check fails
If the conformance test fails, the new SKILL.md is usually missing a required section or frontmatter. Add the missing piece and run the test again. If gbrain check-resolvable reports the skill as unreachable, add a row for it in a fitting category in skills/RESOLVER.md and run the check again.
For any gbrain error code, exit code, [AGENT] block or notice block, the skill directs the agent to follow the agent operator protocol at ../conventions/agent-operator-protocol.md.
- Conformance test fails: add the missing section or frontmatter, then re-run
- check-resolvable reports unreachable: add a RESOLVER row, then re-run
gbrain check-resolvableWhat are the safety notes?
The skill is marked as mutating, meaning it changes files: it writes a new SKILL.md and edits skills/manifest.json and skills/RESOLVER.md. Review those edits before committing them. The skill runs no scripts and makes no network calls, so its effects are limited to the files in the repository and the test run.
Common mistakes the skill is designed to prevent include creating a skill that overlaps an existing one, skipping the MECE check, leaving out triggers in the frontmatter, not updating the manifest and resolver, and omitting an Anti-Patterns section.
- Mutating: true, so it edits repository files
- Runs no scripts and uses no network
- Review manifest and resolver changes before committing
What people use it for
- Adding a new task-specific skill to the GBrain skill library in the standard format
- Extending an existing skill with new triggers when the MECE check finds overlap
- Standardising a personal skill library so every skill has the same contract, phases and anti-patterns
- Checking that a new skill is reachable through the resolver using check-resolvable
Frequently asked questions
How do I install the Skill Creator skill?
Download the skill ZIP from this page and unzip it. Place the folder in ~/.claude/skills/ for personal use or in a project's .claude/skills/ folder, or upload the ZIP in the Claude apps under Settings → Capabilities → Skills.
What do I need to run Skill Creator?
You need the Bun runtime, a GBrain repository containing skills/manifest.json, skills/RESOLVER.md and the conformance test file, and GBrain tools named search and list_pages. Without the surrounding repository files, the skill will not work as intended.
Is Skill Creator free to use and what is its licence?
The source material lists the licence as MIT. The source does not state pricing, so check the repository for any cost details before relying on it.
Can I use Skill Creator outside the GBrain project?
The source says it is not suitable for projects outside GBrain, because the manifest, resolver and conformance test paths are specific to that repository. It will not have the files it edits elsewhere.
Does Skill Creator run scripts or access the internet?
No. The source states it runs no scripts and uses no network. It edits SKILL.md, skills/manifest.json and skills/RESOLVER.md, and it runs the conformance test.
Why does the conformance test fail after I create a skill?
The most common cause is a missing required section or frontmatter in the new SKILL.md. Add the missing Contract, Anti-Patterns, Output Format or When it fails section, or the missing frontmatter, then run bun test test/skills-conformance.test.ts again.
Is Skill Creator only for writing skills, or does it run them?
It only helps write new skills. It is not intended for people who just want to use an existing skill.
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Our verdict
Skill Creator is a good fit for GBrain maintainers and developers who want every new skill to follow the same contract, phases and anti-pattern structure. If you only want to use existing skills, or your project is not GBrain, pick a different tool, since this one depends on the repository's manifest, resolver and conformance test.
Download the skill