Use when a framed problem needs root-cause investigation rather than a symptom-level fix, applying Five Whys, Fishbone (Ishikawa), Current Reality Tree, and constraint identification. This should trigger when an issue's Root Cause Analysis point of view needs evaluation, or when a maintainer directly asks to find the root cause of a problem before proposing a fix. Part of Plinth Toolkit
SkillScore70Maintained
Automatic
◆Product Management pack
Last verified 8/20/2026
What it changes
Passed 16 of 23 test cases with the skill, and 12 of 23 without it.
Without skill52%
With skill70%
Checks it passed that the model alone missed
Directs the unverified vendor cause into downstream assumption analysis.
Flags the missing record regarding the skipped load test as an open data gap.
Flags the missing organizational data required to verify the primary constraint.
and 5 more in the full report
5 fixed11 passed either way6 still failing1 broke
Pass-rate lift
+17 pp
Tokens
+36%
Agent turns
0%
Response time
+4%
Model gemini-3.6-flashMeasured 8/20/2026v116 of 23 cases passed with skill
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 5 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 5
Prompt
Here is log evidence from our incident report: Server A CPU hit 100% at 14:00 due to a background cron job 'sync_users' running concurrent with peak web traffic. The cron job was scheduled for 14:00 because its configuration file was modified in release v2.4 without load testing. We do not have records on who modified the config file or why load testing was skipped. Trace the Five Whys for this incident based on this log report and give us the final root cause.
What was checked, without and with the skill
Checked
Without skill
With skill
Stops the Five Whys chain at the unevidenced release step rather than assuming why load testing was skipped.
Missed
Passed
Flags the missing record regarding the skipped load test as an open data gap.
Missed
Passed
case-04 · gemini-3.6-flash · 8/20/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md63 lines2 files
Root Cause Analysis
Guide the identification of root causes, not symptoms, for a framed problem, using Five Whys, Fishbone (Ishikawa), Current Reality Tree, and constraint identification. This is an interactive SKILL.
What is covered in this Skill?
Five Whys for a linear causal chain from a symptom to a root cause
Fishbone (Ishikawa) for categorized candidate causes across multiple dimensions
Current Reality Tree for interconnected causes and effects with a small number of core problems
Constraint identification for the limiting factor holding the current state in place
Choosing the technique(s) proportionate to the problem's complexity
Feeding root-cause findings into 023-assumption-analysis and the remaining Functional Specification lenses
Constraints
Distinguish root causes from symptoms before recommending a fix. When this technique is orchestrated by another workflow, the orchestrator owns clarifying-question sequencing; when applied standalone, ask directly.
MUST read references/022-root-cause-analysis.md before applying Root Cause Analysis guidance
MUST distinguish a symptom (an observed effect) from a root cause (the condition that produces it)
MUST apply Five Whys as a chain of "why" questions grounded in evidence from the problem frame, not assumption
MUST apply Fishbone to organize candidate causes into categories (for example people, process, technology, environment) when more than one causal dimension is plausible
MUST apply Current Reality Tree when multiple symptoms may share one or a small number of core problems connected by cause-effect relationships
MUST identify the constraint limiting the current state, not only the most visible cause
MUST NOT invent a root cause when the available evidence is vague or ambiguous; flag the gap for a clarifying question instead
When to use this skill
Find the root cause of this problem
Apply Five Whys to this issue
Build a Fishbone diagram for this problem
Use Current Reality Tree to connect these symptoms
Identify the constraint limiting the current state
Draft the Root Cause Analysis section of a Functional Specification
Workflow
Read the Reference
Read references/022-root-cause-analysis.md, then identify the symptom(s) evidenced by the problem frame.