Install Skill Tracker

Overview

This skill automates the installation of a skill tracking system for Claude Code projects. The system uses Claude Code hooks to automatically log all skill invocations, their duration, and the prompts that triggered them. This data enables pattern analysis to identify frequently repeated workflows that could become new skills.

When to Use This Skill

Use this skill when:

• Setting up skill usage tracking in a new or existing Claude Code project
• Wanting to analyze which skills are used most frequently
• Monitoring API costs and token usage across skill executions
• Identifying time-consuming skills that may need optimization
• Discovering patterns in work that could be automated with new skills
• Tracking productivity gains and cost efficiency from skill automation
• Understanding prompt cache effectiveness and optimization opportunities

Installation Workflow

Step 1: Create Directory Structure

Create the necessary directories for hooks, scripts, and logs:

mkdir -p .claude/hooks .claude/scripts .claude/activity-logs

Step 2: Install Hook Scripts

Copy the hook scripts from this skill's scripts/ directory to .claude/hooks/:

• track-prompts.sh - Logs user prompts with timestamps and session IDs
• track-skill-start.sh - Logs when skills begin execution
• track-skill-end.sh - Logs skill completion and calculates duration

Make the hook scripts executable:

chmod +x .claude/hooks/*.sh

Step 3: Install Analysis Script

Copy the analysis script from this skill's scripts/ directory to .claude/scripts/:

• analyze-skills.py - Processes logs and generates usage reports

Make the analysis script executable:

chmod +x .claude/scripts/analyze-skills.py

Step 4: Configure Hooks

Copy the settings.json template from this skill's assets/ directory to .claude/settings.json. This configuration registers three hooks:

• UserPromptSubmit - Captures all user prompts
• PreToolUse (Skill matcher) - Logs skill start times
• PostToolUse (Skill matcher) - Logs skill completion times

Step 5: Add Documentation

Copy the README.md from this skill's assets/ directory to .claude/README.md. This provides documentation on:

• What data gets tracked
• How the tracking system works
• How to analyze the logs
• Customization options
• Troubleshooting guide

Step 6: Update .gitignore

Add the activity logs directory to .gitignore to prevent tracking log files:

echo ".claude/activity-logs/" >> .gitignore
echo ".claude/settings.local.json" >> .gitignore

Step 7: Verify Installation

Confirm all files are in place:

ls -la .claude/hooks/
ls -la .claude/scripts/
cat .claude/settings.json

Using the Tracking System

Automatic Logging

After installation, the tracking system operates automatically:

1. Use skills normally through Claude Code
2. Each skill invocation is logged with timestamp, duration, token usage, and triggering prompt
3. Logs accumulate in .claude/activity-logs/ as JSONL files

What Gets Tracked (v1.2):

• Skill name and invocation time
• Execution duration (in seconds)
• Token usage metrics:
  • Input tokens (new content)
  • Output tokens (generated response)
  • Cache read tokens (from prompt cache)
  • Cache creation tokens (creating cache entries)
  • Total tokens (sum of all above)
• User prompt that triggered the skill
• Session ID for correlation

Analyzing Usage Data

Run the analysis scripts to generate insights:

Pattern and Performance Analysis:

.claude/scripts/analyze-skills.py

Token Usage and Cost Analysis (v1.2):

.claude/scripts/show-skill-tokens.sh

The analysis reports include:

• Skill frequency - Most commonly used skills
• Performance metrics - Average and total duration per skill
• Token usage metrics - Input/output/cache tokens per skill (NEW)
• Cost estimation - Calculate API costs based on token usage (NEW)
• Cache efficiency - Identify cache hit rates and optimization opportunities (NEW)
• Prompt patterns - Common prompts that trigger skills
• Usage history - Recent skill invocations with details
• Insights - Suggestions for optimization and new skill opportunities

Example Analysis Output

# Skill Usage Analysis Report

**Total skill invocations:** 15

## Most Used Skills

- **microsim-p5**: 7x
- **learning-graph-generator**: 5x
- **glossary-generator**: 3x

## Skill Performance (Average Duration)

- **learning-graph-generator**
  - Average: 2m 34s
  - Total time: 12m 50s
  - Invocations: 5x

## Insights & Suggestions

### Frequently Used Skills
- **microsim-p5** (7x): Could benefit from optimization or templates

### Total Time Automated
Skills have automated **45m 23s** of work

Log Data Format

The system creates two JSONL log files:

prompts.jsonl

Logs user prompts with session correlation:

{"timestamp": "2025-11-22 14:23:45", "epoch": "1732299825", "session": "abc123", "prompt": "create a learning graph"}

skill-usage.jsonl

Logs skill start/end events with duration and token usage:

{"timestamp": "2025-11-22 14:23:46", "epoch": "1732299826", "session": "abc123", "skill": "learning-graph-generator", "event": "start"}
{"timestamp": "2025-11-22 14:26:20", "epoch": "1732299980", "session": "abc123", "skill": "learning-graph-generator", "event": "end", "duration_seconds": "154", "input_tokens": 12000, "output_tokens": 8500, "total_tokens": 84200, "cache_read_tokens": 62400, "cache_creation_tokens": 1300}

Customization Options

Global vs Project-Specific Tracking

Current setup: Project-specific tracking (logs in .claude/activity-logs/)

For global tracking across all projects:

1. Move settings.json to ~/.claude/settings.json
2. Update LOG_DIR in hook scripts to ~/.claude/activity-logs
3. Analysis script will aggregate data from all projects

Tracking Additional Metrics

Extend the hook scripts to capture:

• All tool usage (not just skills)
• Error rates and failures
• Custom metadata fields
• Project-specific context

Hooks receive full JSON context via stdin with tool names, parameters, and outputs.

Privacy & Security

All tracking data is stored locally:

• No data transmission to external services
• Logs remain in .claude/activity-logs/
• Automatically excluded from git via .gitignore

To delete all tracking data:

rm -rf .claude/activity-logs

Troubleshooting

JSON Parsing Errors

IMPORTANT FIX (v1.1): The hook scripts now use jq -nc instead of jq -n to generate compact JSON output. This is critical for proper JSONL format.

If you encounter errors like:

json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes

Your existing log files may have pretty-printed JSON. Fix with:

jq -c '.' .claude/activity-logs/prompts.jsonl > temp && mv temp .claude/activity-logs/prompts.jsonl
jq -c '.' .claude/activity-logs/skill-usage.jsonl > temp && mv temp .claude/activity-logs/skill-usage.jsonl

Hooks Not Executing

Verify hook configuration:

cat .claude/settings.json

Check script permissions:

ls -l .claude/hooks/*.sh

No Log Files Created

Ensure directories exist:

mkdir -p .claude/activity-logs

Use a skill to trigger logging, then check:

ls -la .claude/activity-logs/

Analysis Shows No Data

Logs are created only after skill usage. Run any skill first, then execute the analysis script.

Detailed Troubleshooting

For comprehensive troubleshooting, see the README.md in this skill directory, which includes:

• JSONL format requirements and the -c flag fix
• Common issues and solutions
• Hook debugging techniques
• Custom analysis queries

Resources

This skill includes:

scripts/

• track-prompts.sh - Bash hook to log user prompts
• track-skill-start.sh - Bash hook to log skill start times
• track-skill-end.sh - Bash hook to log skill completion, duration, and tokens (v1.2)
• analyze-skills.py - Python script to analyze logs and generate reports
• show-skill-tokens.sh - Bash script to display token usage and cost metrics (v1.2)

assets/

• settings.json - Hook configuration template for .claude/settings.json
• README.md - Complete documentation for the tracking system