skill-optimizer
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):
Skilltool_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_metaevents → extractbase_instructionsfor skill loading evidenceresponse_itemevents → assistant outputs (workflow tracking)event_msgevents → tool execution and skill-related events- User messages from
turn_contextevents (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:
- Extract the skill's defined steps from SKILL.md
- Search the assistant messages in that session for step markers (Step N, specific output formats defined in the skill)
- 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.