evidence-driven-debugging

evidence-driven-debugging is a skill for Claude Code, Codex from duthaho/claudekit. It costs 87 tokens per session (2,413 once invoked), scanned A, original, MIT.

A debugging workflow for testing a specific theory about a software problem with runtime evidence such as logs, breakpoints, or probes.

In plain words
What is it for?
It helps investigate asynchronous or distributed systems, bugs that appear only after deployment, and runtime behaviour that is difficult to observe directly.
Why use it?
It prevents unfocused trial and error and keeps a record of what was tested and what the evidence showed.

Skill for Claude CodeCodex

Part of the claudekit plugin — 15 skills, 8 agents shipped together

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/duthaho/claudekit/evidence-driven-debugging
Any agent
npx skills add duthaho/claudekit --skill evidence-driven-debugging
Clone the repo
git clone --depth 1 https://github.com/duthaho/claudekit

Made for: Claude Code, Codex.

Or install claudekit, the plugin that ships this one along with the rest of its 15 skills, 8 agents.

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 evidence-driven-debugging

README.md
[![agentmods](https://agentmods.dev/badge/skills/duthaho/claudekit/evidence-driven-debugging.svg)](https://agentmods.dev/skills/duthaho/claudekit/evidence-driven-debugging)
Your own site
<a href="https://agentmods.dev/skills/duthaho/claudekit/evidence-driven-debugging"><img src="https://agentmods.dev/badge/skills/duthaho/claudekit/evidence-driven-debugging.svg" alt="Measured on agentmods" height="20"></a>
Per session 87 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,413 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 $0.00087 $0.02413
Opus 5 $0.00044 $0.01207
Sonnet 5 $0.00017 $0.00483
Haiku 4.5 $0.00009 $0.00241

Measured 4d ago against content hash adb9e10e821b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

evidence-driven-debugging 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.

skills/evidence-driven-debugging/SKILL.md · 184 lines

How it starts

The opening of the file, as written. The whole thing — 184 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Evidence-Driven Debugging

Overview

The active-debugging companion to investigate-root-cause. Where investigate produces a written hypothesis, evidence-driven-debugging is the workflow for testing that hypothesis with real instrumentation: logs, breakpoints, prints, debugger sessions, runtime probes. The skill exists because the most common debugging-phase failure is the engineer who runs through three or four mental hypotheses without writing anything down, ends up where they started, and can't reconstruct what they tried. Evidence-driven debugging keeps a paper trail. Used inside Phase 3 of investigate-root-cause, but invocable directly when an existing hypothesis just needs runtime testing.

When to Use

  • You have a hypothesis from investigate-root-cause and need to test it
  • You're debugging in a system that's hard to step through (async, distributed, multi-process)
  • You've added logs/prints to test a theory and need to organize what you learn
  • A bug only reproduces in a deployed environment, not locally
  • You're about to do "let me just add some console.logs" — pause and use this skill to keep them organized

When NOT to Use

  • You don't have a hypothesis yet — go to investigate-root-cause Phase 2 first
  • The bug is in code you can step through with a debugger and the path is short
  • The fix is one line and obvious from reading; debugging instrumentation is overkill

Process

Step 1: State the hypothesis to test

Goal: Be explicit about what runtime evidence will confirm or refute.

Inputs: A hypothesis (from investigate-root-cause Phase 2 or your own prior thinking).

Actions:

  1. Write the hypothesis as one sentence: The bug occurs because [X] causes [Y] when [Z].
  2. Decide what runtime evidence would confirm it: a value at a specific line, a sequence of events, an absence of an expected log line.
  3. Decide what would refute it: the value isn't what you predicted, the sequence is different, the expected event happens but the bug still occurs.

Read the full file on GitHub · 184 lines

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. 4d ago First seen · 184 lines · 87 tokens per session scan A adb9e10e821b

Subscribe to this mod's changes

evidence-driven-debugging is a skill published in the GitHub repository duthaho/claudekit (97 stars, last pushed 1mo ago), licensed MIT. It adds 87 tokens to every session and 2,413 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 2026-08-30.

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