Claude Mastery

When to Use This Skill

• Use when skills are not triggering as expected or seem broken
• Use when you want to audit and improve your skill library's quality
• Use when you want to understand which skills are underperforming or wasting context tokens

Rules

• Read-only: never modify skill files. Only output report.
• All 8 dimensions: do not skip any. If data is insufficient, report "N/A — insufficient session data" rather than omitting.
• Quantify: "you had 12 research tasks last week but the skill never triggered" beats "you often do research".
• Suggest, don't prescribe: give specific wording suggestions for description improvements, but frame as suggestions.
• Show evidence: for undertrigger claims, quote the actual user message that should have triggered the skill.
• Evidence-based suggestions: when suggesting description rewrites, cite the specific research finding that motivates the change (e.g., "front-load trigger keywords — MCP study shows 3.6x selection rate improvement").

Overview

Analyze skills using historical session data + static quality checks, output a diagnostic report with P0/P1/P2 prioritized fixes. Scores each skill on a 5-point composite scale across 8 dimensions.

CSO (Claude/Agent Search Optimization) = writing skill descriptions so agents select the right skill at the right time. This skill checks for CSO violations.

Usage

• /optimize-skill → scan all skills
• /optimize-skill my-skill → single skill
• /optimize-skill skill-a skill-b → multiple specified skills

Data Sources

Auto-detect the current agent platform and scan the corresponding paths:

Source	Claude Code	Codex	Shared
Session transcripts	~/.claude/projects/**/*.jsonl	~/.codex/sessions/**/*.jsonl	—
Skill files	~/.claude/skills/*/SKILL.md	~/.codex/skills/*/SKILL.md	~/.agents/skills/*/SKILL.md

Platform detection: Check which directories exist. Scan all available sources — a user may have both Claude Code and Codex installed.

Workflow

Identify target skills
        ↓
Collect session data (python3 scripts scan JSONL transcripts)
        ↓
Run 8 analysis dimensions
        ↓
Compute composite scores
        ↓
Output report with P0/P1/P2

Step 1: Identify Target Skills

Scan skill directories in order: ~/.claude/skills/, ~/.codex/skills/, ~/.agents/skills/. Deduplicate by skill name (same name in multiple locations = same skill). For each, read SKILL.md and extract:

• name, description (from YAML frontmatter)
• trigger keywords (from description field)
• defined workflow steps (Step 1/2/3... or ### sections under Workflow)
• word count

If user specified skill names, filter to only those.

Step 2: Collect Session Data

Use python3 scripts via Bash to scan session JSONL files. Extract:

Claude Code sessions (~/.claude/projects/**/*.jsonl):

• Skill tool_use calls (which skills were invoked)
• User messages (full text)
• Assistant messages after skill invocation (for workflow tracking)
• User messages after skill invocation (for reaction analysis)

Codex sessions (~/.codex/sessions/**/*.jsonl):

• session_meta events → extract base_instructions for skill loading evidence
• response_item events → assistant outputs (workflow tracking)
• event_msg events → tool execution and skill-related events
• User messages from turn_context events (for reaction analysis)

Note: Codex injects skills via context rather than explicit Skill tool calls. Skill loading (present in base_instructions) does NOT equal active invocation. To detect actual use, search for skill-specific workflow markers (step headers, output formats) in response_item content within that session. A skill is "invoked" only if the agent produced output following the skill's defined workflow.

Aggregated:

• Per-skill: invocation count, trigger keyword match count
• Per-skill: user reaction sentiment after invocation
• Per-skill: workflow step completion markers

Step 3: Run 8 Analysis Dimensions

You MUST run ALL 8 dimensions. The baseline behavior without this skill is to skip dimensions 4.2, 4.3, 4.5b, and 4.8. These are the most valuable dimensions — do not skip them.

4.1 Trigger Rate

Count how many times each skill was actually invoked vs how many times its trigger keywords appeared in user messages.

Claude Code: count Skill tool_use calls in transcripts. Codex: count sessions where the agent produced output following the skill's workflow markers (not merely loaded in context).

Diagnose:

• Never triggered → skill may be useless or trigger words wrong
• Keywords match >> actual invocations → undertrigger problem, description needs work
• High frequency → core skill, worth optimizing

4.2 Post-Invocation User Reaction

This dimension is critical and easy to skip. Do not skip it.

After a skill is invoked in a session, read the user's next 3 messages. Classify:

• Negative: "no", "wrong", "never mind", "not what I wanted", user interrupts
• Correction: user re-describes their intent, manually overrides skill output
• Positive: "good", "ok", "continue", "nice", user follows the workflow
• Silent switch: user changes topic entirely (likely false positive trigger)

Report per-skill satisfaction rate.

4.3 Workflow Completion Rate

This dimension is critical and easy to skip. Do not skip it.

For each skill invocation found in session data:

1. Extract the skill's defined steps from SKILL.md
2. Search the assistant messages in that session for step markers (Step N, specific output formats defined in the skill)
3. Calculate: how far did execution get?

Report: {skill-name} (N steps): avg completed Step X/N (Y%)

If a specific step is frequently where execution stops, flag it.

4.4 Static Quality Analysis

Check each SKILL.md against these 14 rules:

Check	Pass Criteria
Frontmatter format	Only name + description, total < 1024 chars
Name format	Letters, numbers, hyphens only
Description trigger	Starts with "Use when..." or has explicit trigger conditions
Description workflow leak	Description does NOT summarize the skill's workflow steps (CSO violation)
Description pushiness	Description actively claims scenarios where it should be used, not just passive
Overview section	Present
Rules section	Present
MUST/NEVER density	Count ALL-CAPS directive words; >5 per 100 words = flag
Word count	< 500 words (flag if over)
Narrative anti-pattern	No "In session X, we found..." storytelling
YAML quoting safety	description containing : must be wrapped in double quotes
Critical info position	Core trigger conditions and primary actions must be in the first 20% of SKILL.md
Description 250-char check	Primary trigger keywords must appear within the first 250 characters of description
Trigger condition count	≤ 2 trigger conditions in description is ideal

4.5a False Positive Rate (Overtrigger)

Skill was invoked but user immediately rejected or ignored it.

4.5b Undertrigger Detection

This is the highest-value dimension. For each skill, extract its capability keywords (not just trigger keywords — what the skill CAN do). Then scan user messages for tasks that match those capabilities but where the skill was NOT invoked.

Report: which user messages SHOULD have triggered the skill but didn't, and suggest description improvements.

Compounding Risk Assessment: For skills with chronic undertriggering (0 triggers across 5+ sessions where relevant tasks appeared), flag as "compounding risk" — undertriggered skills cannot self-improve through usage feedback, causing the gap to widen over time. Recommend immediate description rewrite as P0.

4.6 Cross-Skill Conflicts

Compare all skill pairs:

• Trigger keyword overlap (same keywords in two descriptions)
• Workflow overlap (two skills teach similar processes)
• Contradictory guidance

4.7 Environment Consistency

For each skill, extract referenced:

• File paths → check if they exist (test -e)
• CLI tools → check if installed (which)
• Directories → check if they exist

Flag any broken references.

4.8 Token Economics

This dimension is critical and easy to skip. Do not skip it.

For each skill:

• Word count (from Step 1)
• Trigger frequency (from 4.1)
• Cost-effectiveness = trigger count / word count
• Flag: large + never-triggered skills as candidates for removal or compression

Progressive Disclosure Tier Check: Evaluate each skill against the 3-tier loading model:

• Tier 1 (frontmatter): ~100 tokens. Check: is description ≤ 1024 chars?
• Tier 2 (SKILL.md body): <500 lines recommended. Check: word count.
• Tier 3 (reference files): loaded on demand. Check: does skill use reference files for detailed content, or cram everything into SKILL.md?

Flag skills that put 500+ words in SKILL.md without using reference files as "poor progressive disclosure".

Step 4: Composite Score

Rate each skill on a 5-point scale:

Score	Meaning
5	Healthy: high trigger rate, positive reactions, complete workflows, clean static
4	Good: minor issues in 1-2 dimensions
3	Needs attention: significant gap in 1 dimension or minor gaps in 3+
2	Problematic: never triggered, or negative user reactions, or major static issues
1	Broken: doesn't work, references missing, or fundamentally misaligned

Scored dimensions (weighted average):

• Trigger rate: 25%
• User reaction: 20%
• Workflow completion: 15%
• Static quality: 15%
• Undertrigger: 15%
• Token economics: 10%

Qualitative dimensions (reported but not scored):

• 4.5a Overtrigger: reported as count + examples
• 4.6 Cross-Skill Conflicts: reported as conflict pairs
• 4.7 Environment Consistency: reported as pass/fail per reference

Report Format

# Skill Optimization Report
**Date**: {date}
**Scope**: {all / specified skills}
**Session data**: {N} sessions, {date range}

## Overview
| Skill | Triggers | Reaction | Completion | Static | Undertrigger | Token | Score |
|-------|----------|----------|------------|--------|--------------|-------|-------|
| example-skill | 2 | 100% | 86% | B+ | 1 miss | 486w | 4/5 |

## P0 Fixes (blocking usage)
1. ...

## P1 Improvements (better experience)
1. ...

## P2 Optional Optimizations
1. ...

## Per-Skill Diagnostics
### {skill-name}
#### 4.1 Trigger Rate
...
#### 4.2 User Reaction
...
(all 8 dimensions)

Research Background

The analysis dimensions in this report are grounded in the following research:

• Undertrigger detection: Memento-Skills (arXiv:2603.18743) — skills as structured files require accurate routing; unrouted skills cannot self-improve via the read-write learning loop
• Description quality: MCP Description Quality (arXiv:2602.18914) — well-written descriptions achieve 72% tool selection rate vs. 20% random baseline (3.6x improvement)
• Information position: Lost in the Middle (Liu et al., TACL 2024) — U-shaped LLM attention curve
• Format impact: He et al. (arXiv:2411.10541) — format changes alone can cause 9-40% performance variance
• Instruction compliance: IFEval (arXiv:2311.07911) — LLMs struggle with multi-constraint prompts

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.