logging

logging is a skill for Claude Code, Codex from eaescob/resiliency_skills. It costs 81 tokens per session (1,063 once invoked), scanned A, original, Apache-2.0.

A skill for adding structured application logs: machine-readable JSON records with levels, useful context, error tracking, and trace links. It covers Next.js, Express, React, and Go.

In plain words
What is it for?
It is for setting up production logging, choosing DEBUG, INFO, WARN, or ERROR levels, adding request or trace identifiers, tracking errors, and debugging applications.
Why use it?
It helps developers find and understand failures in running software instead of searching through inconsistent text logs. It also guides them away from logging passwords, tokens, and personal data.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/eaescob/resiliency_skills/logging
Any agent
npx skills add eaescob/resiliency_skills --skill logging
Clone the repo
git clone --depth 1 https://github.com/eaescob/resiliency_skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for logging

README.md
[![agentmods](https://agentmods.dev/badge/skills/eaescob/resiliency_skills/logging.svg)](https://agentmods.dev/skills/eaescob/resiliency_skills/logging)
Your own site
<a href="https://agentmods.dev/skills/eaescob/resiliency_skills/logging"><img src="https://agentmods.dev/badge/skills/eaescob/resiliency_skills/logging.svg" alt="Measured on agentmods" height="20"></a>
Per session 81 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,063 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00081 $0.01063
Opus 5 $0.00041 $0.00531
Sonnet 5 $0.00016 $0.00213
Haiku 4.5 $0.00008 $0.00106

Measured 5d ago against content hash 6804a8199edd, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

logging scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/logging/SKILL.md · 170 lines

How it starts

The opening of the file, as written. The whole thing — 170 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Logging

Implement structured logging for debugging, monitoring, and troubleshooting.

Logging Principles

  1. Structured JSON - Machine-parseable logs for aggregation
  2. Appropriate levels - DEBUG, INFO, WARN, ERROR
  3. Context enrichment - Include request ID, user ID, trace ID
  4. No sensitive data - Never log passwords, tokens, PII
  5. Actionable messages - Include what happened and context

Log Levels

Level When to Use
ERROR Failures requiring immediate attention
WARN Unexpected conditions that don't stop execution
INFO Significant business events (user actions, API calls)
DEBUG Detailed diagnostic info (development only)

Framework References

Next.js

See references/frameworks/nextjs.md for:

  • Server-side logging setup
  • API route logging
  • Client-side error boundary logging

Express

See references/frameworks/express.md for:

  • Winston/Pino configuration
  • Request logging middleware
  • Error handler logging

Go

See references/frameworks/go.md for:

  • slog (standard library) setup
  • Structured logging patterns
  • Middleware logging

Quick Setup

Node.js with Pino (Recommended)

// lib/logger.ts
import pino from "pino"

export const logger = pino({
  level: process.env.LOG_LEVEL || "info",
  formatters: {
    level: (label) => ({ level: label }),
  },
  base: {
    service: process.env.SERVICE_NAME || "my-service",
    env: process.env.NODE_ENV,
  },
})

// Usage
logger.info({ userId: user.id, action: "login" }, "User logged in")
logger.error({ err, orderId }, "Failed to process order")

Go with slog

import (
    "log/slog"
    "os"
)

var logger = slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
    Level: slog.LevelInfo,
}))

// Usage
logger.Info("user logged in", "userId", user.ID, "action", "login")
logger.Error("failed to process order", "error", err, "orderId", orderID)

Read the full file on GitHub · 170 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 170 lines · 81 tokens per session scan A 6804a8199edd

Subscribe to this mod's changes

logging is a skill published in the GitHub repository eaescob/resiliency_skills (2 stars, last pushed 7mo ago), licensed Apache-2.0. It adds 81 tokens to every session and 1,063 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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