observability-driven-testing

observability-driven-testing is a skill for Claude Code, Codex from petrkindlmann/qa-skills. It costs 149 tokens per session (5,045 once invoked), scanned A, original, MIT.

A guide for using production information—traces, logs, and reported errors—to decide what tests to write and which areas matter most. OpenTelemetry is a standard way to collect traces and other application telemetry.

In plain words
What is it for?
Use it to add traces to test runs, check service calls and error spans, turn Sentry or Datadog errors into tests, and prioritize endpoints based on production evidence.
Why use it?
Test plans can miss failures that real users encounter, while telemetry can show which services, requests, and errors need coverage. This connects observed production behavior with test design and prioritization.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to add traces to test runs, check service calls and…

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Install with agentmods
npx agentmods add skills/petrkindlmann/qa-skills/observability-driven-testing
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.

Any agent
npx skills add petrkindlmann/qa-skills --skill observability-driven-testing
Clone the repo
git clone --depth 1 https://github.com/petrkindlmann/qa-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 observability-driven-testing

README.md
[![agentmods](https://agentmods.dev/badge/skills/petrkindlmann/qa-skills/observability-driven-testing.svg)](https://agentmods.dev/skills/petrkindlmann/qa-skills/observability-driven-testing)
Your own site
<a href="https://agentmods.dev/skills/petrkindlmann/qa-skills/observability-driven-testing"><img src="https://agentmods.dev/badge/skills/petrkindlmann/qa-skills/observability-driven-testing.svg" alt="Measured on agentmods" height="20"></a>
Per session 149 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,045 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 $0.00149 $0.05045
Opus 5 $0.00075 $0.02523
Sonnet 5 $0.00030 $0.01009
Haiku 4.5 $0.00015 $0.00505

Measured 7d ago against content hash e5a76618c95f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

observability-driven-testing 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 7d 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/observability-driven-testing/SKILL.md · 342 lines

How it starts

The opening of the file, as written. The whole thing — 342 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Quick Route

Situation Go to
Make test execution emit traces correlated with the app OTel test-runner setup (references/trace-assertions.md)
Assert which services were called / no error spans / latency Traces as Test Evidence
Turn a Sentry/Datadog error into a test Production Error to Test Pipeline
Decide which endpoints need tests next Telemetry-Driven Test Prioritization
A trace assertion is flaky or a span never arrives Failure Modes

Discovery Questions

Check .agents/qa-project-context.md first. If it exists, use it as context and skip questions already answered there.

Observability stack:

  • What APM/tracing tool is in place? (Datadog, New Relic, Honeycomb, Splunk Observability/SignalFx, ServiceNow Cloud Observability — formerly Lightstep, Dash0, Jaeger, Grafana Tempo, OpenTelemetry-native) — determines how you pull traces and which query syntax the diagnosis workflow uses.
  • Is OpenTelemetry instrumented in the application, and which services? — un-instrumented services are invisible and untestable via traces.
  • What logging infrastructure exists? (ELK, Loki, CloudWatch, Datadog Logs) — sets where log-by-trace-ID correlation happens.
  • Are structured logs used, or free-form text? — structured logs are parseable into test gaps; free-form needs a fingerprinting step first.

Tracing maturity:

  • Are distributed traces available across service boundaries? — without them, only single-service span assertions are possible.
  • What is the trace sampling rate? (100%, 10%, head-based, tail-based) — probabilistic sampling will randomly drop the trace a test asserts on; you must force-sample test traffic (see Failure Modes).
  • Can you search traces by error status, latency threshold, or custom attributes?
  • Are traces correlated with logs and metrics? — enables exemplars (metric → representative trace ID), which makes prioritization concrete.

Read the full file on GitHub · 342 lines

Files

What ships with it

2 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. 7d ago First seen · 342 lines · 149 tokens per session scan A e5a76618c95f

Subscribe to this mod's changes

observability-driven-testing is a skill published in the GitHub repository petrkindlmann/qa-skills (110 stars, last pushed 2mo ago), licensed MIT. It adds 149 tokens to every session and 5,045 once invoked, about $0.0007 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 2026-08-30.

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