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The skill creator skill for Claude

Skill creator is Anthropic's skill for writing skills. It takes Claude from an idea or an existing conversation to a drafted SKILL.md, then tests it: runs the same prompts with and without the skill, grades the results, shows them in a review viewer, and rewrites the skill from your feedback.

Source

When the agent reaches for it

The agent keeps every installed skill's description in view and loads the full instructions when a request matches. This is the description it reads:

Create new skills, modify and improve existing skills, and measure skill performance. Use when users want to create a skill from scratch, edit, or optimize an existing skill, run evals to test a skill, benchmark skill performance with variance analysis, or optimize a skill's description for better triggering accuracy.

What sets it apart from writing a SKILL.md by hand

Skill creator treats a skill as something you measure. Every test prompt runs twice, once with the skill and once without, and both runs start in the same turn so they finish together. Claude drafts assertions while the runs finish, grades them, and opens a viewer where you read the outputs side by side.

The second half is triggering. A skill that never loads does nothing, and the only thing the agent sees before loading it is the description. Skill creator generates queries that should and should not trigger the skill, runs an optimization loop over the description, and applies the version that triggers most accurately.

  • Bundled grader, comparator and analyzer prompts for blind comparisons.
  • Benchmarks with variance, so one lucky run does not decide the change.
  • Adjusts its jargon to the person it is working with.

What the instructions cover

The sections of its SKILL.md, in order.

  • Communicating with the user
  • Creating a skill
  • Running and evaluating test cases
  • Improving the skill
  • Advanced: Blind comparison
  • Description Optimization
  • Claude.ai-specific instructions
  • Cowork-Specific Instructions
  • Reference files

What ships with it

Besides SKILL.md, the folder carries these. The agent opens them only when a step in the instructions calls for one.

  • agents/ 3 files · 26 KB
  • assets/ 1 file · 7 KB
  • eval-viewer/ 2 files · 60 KB
  • references/ 1 file · 12 KB
  • scripts/ 9 files · 72 KB

Install the skill creator skill

In Claude Code, run this in a session. It comes from the publisher's own instructions.

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

License: Apache-2.0.

Questions people ask

How do I install the skill creator skill?

In Claude Code, run /plugin marketplace add anthropics/skills, then /plugin install example-skills@anthropic-agent-skills.

When does the agent use the skill creator skill?

When a request matches its description. The agent keeps only the name and description of each installed skill in view, and reads the full instructions when a task fits. You can also ask for it by name.

Start with one machine.

Add the others when the work needs them, and the cloud when it has to keep going without you.

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