Usage Logging

What it does

When your agent uses it

• Adding audit trails
• Usage analytics
• Cost tracking to a skill

Example prompts

• “Use the usage-logging skill to implement structured usage logging and audit trails for cost and session tracking”
• “/usage-logging”

Requirements

• Python 3

Workflow steps

3 steps, taken from the first numbered list in SKILL.md.

1. 1Initialize logger for your service
2. 2Log operations after completion
3. 3Query for analytics and debugging

What it can do on your machine

Read from SKILL.md and the folder at commit 9f3eb00. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • jq

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Usage Logging loads about 896 tokens when it runs. Until then it costs about 43 tokens; SKILL.md has 218 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~43

When it runs · the whole SKILL.md, loaded when a task matches

~896

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from athola/claude-night-market at commit 9f3eb00, republished under its MIT licence (© athola). 218 words, ~896 tokens.

name

usage-logging

description

Implements structured usage logging and audit trails for cost and session tracking. Use when adding audit trails, usage analytics, or cost tracking to a skill.

alwaysApply

false

category

infrastructure

tags

logging, usage, audit, metrics, sessions, analytics

provides.infrastructure

usage-logging, session-management, audit-trails

provides.patterns

structured-logging, metrics-collection, cost-tracking

usage_patterns

audit-logging, cost-tracking, usage-analytics, session-management

complexity

beginner

model_hint

fast

estimated_tokens

450

progressive_loading

true

{
  "timestamp": "2025-12-05T10:30:00Z",
  "session_id": "session_1733394600",
  "service": "my-service",
  "operation": "analyze_files",
  "tokens": 5000,
  "success": true,
  "duration_seconds": 2.5,
  "metadata": {}
}

from leyline.usage_logger import UsageLogger

logger = UsageLogger(service="my-service")

logger.log_usage(
    operation="analyze_files",
    tokens=5000,
    success=True,
    duration=2.5,
    metadata={"files": 10},
)

# Recent operations
recent = logger.get_recent_operations(hours=24)

# Usage summary
summary = logger.get_usage_summary(days=7)
print(f"Total tokens: {summary['total_tokens']}")
print(f"Total cost: ${summary['estimated_cost']:.2f}")

# Recent errors
errors = logger.get_recent_errors(count=10)

# In your skill's frontmatter
dependencies: [leyline:usage-logging]

# View recent logs
tail -20 ~/.claude/leyline/usage/my-service.jsonl | jq .

# Query by date
grep "2025-12-05" ~/.claude/leyline/usage/my-service.jsonl

© athola, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 2 other files in plugins/leyline/skills/usage-logging of athola/claude-night-market.

• SKILL.md
• modules/log-formats.md
• modules/session-patterns.md

Open the folder on GitHubat commit 9f3eb00