Skill Creator 🧩 Skill Free

What it does

Skill Creator is the skill in Anthropic's official repository for building new Agent Skills and improving existing ones. When you ask the agent to turn a workflow into a skill, the skill guides it through the whole job. The agent first works out what the skill should do. It then writes the SKILL.md, runs test prompts with and without the skill, and reviews the results with you. It repeats this loop until the skill behaves as intended. If you just want a quick draft, it can skip the formal testing.

What is inside

This is one of the larger skills in the repository. Alongside SKILL.md it ships several parts:

• agents/ with instructions for subagents that grade outputs, run blind A/B comparisons and analyse why one version beat another
• scripts/ with Python tools to run evals, aggregate benchmarks, improve a skill's description so it triggers at the right time, validate a skill and package it
• eval-viewer/, which generates a review page for test results
• references/ with the JSON schemas used by the eval files

The written guidance also covers how skills are structured, how to keep the main file short by moving detail into reference files, and how to write descriptions that trigger reliably.

Works with

It is included in the example-skills plugin of the Anthropic marketplace for Claude Code, and the skill has specific notes for Claude.ai and Cowork. The parts that spawn parallel test runs work best where subagents are available. The skills it produces use the open SKILL.md format.

How to install

/plugin marketplace add anthropics/skills
/plugin install example-skills@anthropic-agent-skills

Maintenance and safety

It is maintained in the main Anthropic skills repository and is licensed Apache 2.0. The eval workflow runs Python scripts and can start many agent runs at once, which uses time and tokens. For a simple skill, ask for the lighter path.

Who should use it

People who keep pasting the same instructions into chats, and teams that want to share a repeatable process as a skill. It helps most once you know which workflow you want to capture.