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skill-creator

Guide for creating effective skills. This skill should be used when users want to create a new skill (or update an existing skill) that extends Gemini CLI's capabilities with specialized knowledge, workflows, or tool integrations.

80

1.29x
Quality

52%

Does it follow best practices?

Impact

100%

1.29x

Average score across 6 eval scenarios

SecuritybySnyk

Passed

No known issues

Optimize this skill with Tessl

npx tessl skill review --optimize ./packages/core/src/skills/builtin/skill-creator/SKILL.md
SKILL.md
Quality
Evals
Security

Quality

Content

47%

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

This skill has a well-structured 7-step workflow with clear sequencing and validation, but it significantly violates its own core principle of conciseness. The content is verbose with extensive explanations of concepts an AI agent would already understand, and it fails to practice the progressive disclosure it preaches—keeping detailed reference material inline rather than splitting it into reference files. The actionability is moderate: good for the mechanical steps (init, package, install) but vague for the creative core of writing effective skill content.

Suggestions

Cut the 'About Skills' and 'What Skills Provide' sections drastically—Gemini CLI doesn't need to be told what skills are or why they exist. Move straight to creation principles and process.

Move the detailed descriptions of bundled resource types (scripts/, references/, assets/) and progressive disclosure patterns into a references/ file, keeping only a brief summary in SKILL.md—practice what the skill preaches.

Add a concrete, complete SKILL.md example (a real mini-skill from start to finish) rather than only showing fragments, to make the writing guidance more actionable.

Remove redundant explanations like 'Think of them as onboarding guides' and 'Think of Gemini CLI as exploring a path'—these metaphors consume tokens without adding actionable value.

DimensionReasoningScore

Conciseness

The skill is extremely verbose at ~400+ lines, with significant portions explaining concepts that Gemini CLI already knows (what PDFs are, what scripts do, what assets are). There are lengthy explanations of basic concepts like 'what skills provide,' extensive bullet-point descriptions of resource types, and redundant elaboration throughout. Much of this could be cut by 50%+ without losing actionable content.

1 / 3

Actionability

The skill provides concrete commands for init and packaging scripts, and includes specific directory structures and naming conventions. However, the actual SKILL.md writing guidance is largely abstract ('write instructions for using the skill'), the code examples are illustrative rather than executable, and the core creative task of writing good skill content lacks concrete templates or copy-paste-ready patterns.

2 / 3

Workflow Clarity

The 7-step skill creation process is clearly sequenced with explicit ordering ('Follow these steps in order, skipping only if there is a clear reason'), includes validation via the packaging script (Step 5), has clear skip conditions for steps, and includes an iteration feedback loop in Step 7. The packaging step explicitly validates before proceeding.

3 / 3

Progressive Disclosure

The skill references external files (references/workflows.md, references/output-patterns.md) and describes progressive disclosure patterns well conceptually. However, the SKILL.md itself is a monolithic wall of text that violates its own advice about keeping SKILL.md under 500 lines and splitting content. Much of the detailed guidance about resource types, progressive disclosure patterns, and examples could be moved to reference files.

2 / 3

Total

8

/

12

Passed

Description

57%

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

The description successfully addresses both 'what' and 'when' with an explicit trigger clause, which is its main strength. However, it is weak on specificity—it reads more like a vague summary than a concrete list of actions the skill performs. The reference to 'Gemini CLI' rather than Claude is also concerning and may cause selection confusion.

Suggestions

Add specific concrete actions the skill performs, e.g., 'Generates SKILL.md files with proper YAML frontmatter, writes step-by-step instructions, and defines trigger conditions for skill selection.'

Include more natural trigger term variations such as 'SKILL.md', 'skill file', 'write a skill', 'skill template', 'add capability'.

Clarify the target platform—the description mentions 'Gemini CLI' which conflicts with the Claude skill ecosystem and could reduce distinctiveness.

DimensionReasoningScore

Specificity

The description uses vague language like 'Guide for creating effective skills' and 'extends capabilities with specialized knowledge, workflows, or tool integrations.' It does not list concrete actions such as 'generate YAML frontmatter,' 'write markdown instructions,' or 'define trigger conditions.'

1 / 3

Completeness

It answers both 'what' (guide for creating effective skills) and 'when' (when users want to create a new skill or update an existing skill), with an explicit 'Use when' equivalent clause specifying the trigger conditions.

3 / 3

Trigger Term Quality

It includes some relevant keywords like 'create a new skill,' 'update an existing skill,' and 'skill' itself, which users might naturally say. However, it misses common variations like 'SKILL.md,' 'skill file,' 'write a skill,' 'add a skill,' or 'skill template.'

2 / 3

Distinctiveness Conflict Risk

The term 'skill' provides some distinctiveness, but the description is broad enough ('specialized knowledge, workflows, or tool integrations') that it could overlap with general documentation or configuration skills. Also, it references 'Gemini CLI' which may cause confusion if this is meant for Claude.

2 / 3

Total

8

/

12

Passed

Validation

100%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation11 / 11 Passed

Validation for skill structure

No warnings or errors.

Repository
google-gemini/gemini-cli
Reviewed

Table of Contents

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