observability

observability is a cursor rule for Cursor from mhmdreza-rafiei/agent-tools. It costs 21 tokens per session (408 once invoked), scanned A, original, MIT.

A set of observability rules for production code, covering logs, metrics, and traces. Observability means making a running system understandable from its recorded behavior.

In plain words
What is it for?
It guides instrumentation for endpoints, jobs, queues, and workers, including structured logs, counters, latency measurements, and trace spans.
Why use it?
It helps diagnose errors, slow requests, retries, and queue problems without logging sensitive data or overwhelming operators with noise.

Cursor rule for Cursor

Written for Cursor: a Cursor rule (.mdc).

Good fit It guides instrumentation for endpoints, jobs, queues, and workers, including structured logs, counters, latency measurements, and trace spans.

Compare 6 cursor rules from other repositories ↓
Install with agentmods
npx agentmods add rules/mhmdreza-rafiei/agent-tools/observability
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.

Clone the repo
git clone --depth 1 https://github.com/mhmdreza-rafiei/agent-tools

Made for: Cursor.

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 observability

README.md
[![agentmods](https://agentmods.dev/badge/rules/mhmdreza-rafiei/agent-tools/observability/github.svg)](https://agentmods.dev/rules/mhmdreza-rafiei/agent-tools/observability)
Your own site
<a href="https://agentmods.dev/rules/mhmdreza-rafiei/agent-tools/observability"><img src="https://agentmods.dev/badge/rules/mhmdreza-rafiei/agent-tools/observability/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for observability

Your own site · 80×15
<a href="https://agentmods.dev/rules/mhmdreza-rafiei/agent-tools/observability"><img src="https://agentmods.dev/badge/rules/mhmdreza-rafiei/agent-tools/observability.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 21 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 408 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00021 $0.00408
Opus 5 $0.00010 $0.00204
Sonnet 5 $0.00004 $0.00082
Haiku 4.5 $0.00002 $0.00041

Measured 8d ago against content hash f356cb73f6b8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

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 8d 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.

rules/observability.mdc · 48 lines

What it actually says

Observability

Applies when adding or changing a path that runs in production (endpoints, jobs, queues, workers). Load for new services, hot-path changes, incident prep. Not every chat.

Logs

  • Structured logs (JSON), not free-text lines. A log entry has: timestamp, level, event, request_id, and the relevant IDs (user, tenant, order).
  • Log at the boundaries (in / out / error), not every line inside.
  • Never log secrets or PII. Redact before logging.
  • Levels mean what they say: error is actionable, warn is suspicious, info is a normal event. Don't info-spam.

Metrics

  • Counters for events (requests, errors, retries); histograms for distributions (latency, payload size); gauges for current state (queue depth, in-flight requests).
  • Label by route / status / tenant — enough to slice, not so much that cardinality explodes.

Tracing

  • One span per unit of work (one request, one queue job, one DB call).
  • Propagate the trace context across service boundaries (W3C traceparent).
  • The span name is the operation, not the URL ("create_order", not "/v1/orders").

The three together

  • A user reports a slow checkout. Logs find the error; metrics show it's p99 not median; traces show which downstream is the bottleneck. Build for that query.

Do not

  • Add a log line per loop iteration.
  • Use print / console.log for production observability.
  • Ship an endpoint with no request_id — you can't correlate its logs.
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. 8d ago First seen · 48 lines · 21 tokens per session scan A f356cb73f6b8

Subscribe to this mod's changes

observability is a cursor rule published in the GitHub repository mhmdreza-rafiei/agent-tools (5 stars, last pushed 24d ago), licensed MIT. It adds 21 tokens to every session and 408 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 2026-09-03.