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.
npx agentmods add skills/sergei-aronsen/claude-code-toolkit/observabilitynpx skills add sergei-aronsen/claude-code-toolkit --skill observabilitygit clone --depth 1 https://github.com/sergei-aronsen/claude-code-toolkitWrote 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.
[](https://agentmods.dev/skills/sergei-aronsen/claude-code-toolkit/observability)<a href="https://agentmods.dev/skills/sergei-aronsen/claude-code-toolkit/observability"><img src="https://agentmods.dev/badge/skills/sergei-aronsen/claude-code-toolkit/observability.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00025 | $0.02016 |
| Opus 5 | $0.00013 | $0.01008 |
| Sonnet 5 | $0.00005 | $0.00403 |
| Haiku 4.5 | $0.00003 | $0.00202 |
Grade A, and why
Observability 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 4d 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.
How it starts
The opening of the file, as written. The whole thing — 353 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Observability Skill
Load this skill when implementing logging, metrics, tracing, or monitoring.
Rule
OBSERVE WHAT MATTERS, NOT EVERYTHING!
- Log for debugging, not for storage
- Metrics for dashboards and alerts
- Traces for distributed debugging
Three Pillars of Observability
| Pillar | Purpose | Use When |
|---|---|---|
| Logs | Debug specific events | "What happened?" |
| Metrics | Aggregate measurements | "How much/many?" |
| Traces | Request flow across services | "Where did time go?" |
Logging Best Practices
Log Levels
| Level | Use Case | Examples |
|---|---|---|
ERROR |
Failures requiring attention | Unhandled exceptions, failed payments |
WARN |
Potential issues | Retry attempts, deprecated usage |
INFO |
Business events | User registered, order placed |
DEBUG |
Diagnostic details | Function inputs/outputs, SQL queries |
Structured Logging
{
"timestamp": "2024-01-15T10:30:00.000Z",
"level": "info",
"message": "User registered",
"service": "auth-service",
"traceId": "abc123",
"userId": "user_456",
"email": "[email protected]",
"duration_ms": 45
}
Logging Patterns
// Good: Structured with context
logger.info('Order placed', {
orderId: order.id,
userId: user.id,
total: order.total,
items: order.items.length,
});
// Bad: Unstructured
logger.info(`Order ${order.id} placed for user ${user.id}`);
What NOT to Log
- Passwords, tokens, API keys
- Full credit card numbers
- Personal data (GDPR)
- High-frequency debug logs in production
Logger Setup
// Pino (Node.js - fastest)
import pino from 'pino';
const logger = pino({
level: process.env.LOG_LEVEL || 'info',
formatters: {
level: (label) => ({ level: label }),
},
base: {
service: 'my-service',
env: process.env.NODE_ENV,
},
});
Metrics
Metric Types
| Type | Use Case | Example |
|---|---|---|
| Counter | Cumulative count | Requests total, errors total |
| Gauge | Current value | Active connections, queue size |
| Histogram | Distribution | Request duration, response size |
| Summary | Percentiles | p50, p95, p99 latency |
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.
- 4d ago First seen · 353 lines · 25 tokens per session scan A 07a2d1830a61
Observability is a skill published in the GitHub repository sergei-aronsen/claude-code-toolkit (5 stars, last pushed 18d ago), licensed MIT. It adds 25 tokens to every session and 2,016 once invoked, about $0.0001 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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