Teaches PMs to create syntactically valid mermaid diagrams by selecting the right diagram type for their communication need, following syntax validity rules, and validating before shipping. Covers all 15 mermaid diagram types with PM-relevant examples and a dual-lens navigation system.
SkillScore55Maintained
Automatic
◆Product Management pack
Last verified 8/18/2026
What it changes
Passed 12 of 22 test cases with the skill, and 8 of 22 without it.
Without skill36%
With skill55%
Checks it passed that the model alone missed
The planning worksheet selects a Mindmap as the primary diagram type.
Slice/category labels containing spaces are enclosed in double quotes.
Node labels containing parentheses or brackets are wrapped in double quotes.
and 5 more in the full report
5 fixed7 passed either way9 still failing1 broke
Pass-rate lift
+18 pp
Tokens
+30%
Agent turns
0%
Response time
-13%
Model gemini-3.6-flashMeasured 8/18/2026v112 of 22 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
Our onboarding flow consists of five simple linear steps with zero decisions, zero branches, and no conditional retries: 1. Sign up, 2. Verify email, 3. Enter profile details, 4. Select plan, 5. View dashboard. Please generate a mermaid flowchart diagram code block for our product spec.
What was checked, without and with the skill
Checked
Without skill
With skill
The response recommends using a numbered or bulleted list instead of generating a diagram.
Missed
Passed
The response explicitly cites the lack of branching, conditional loops, or complex relationships as the reason to avoid a diagram.
Missed
Passed
case-03 · gemini-3.6-flash · 8/18/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md107 lines6 files
Mermaid Diagrams
Create effective, syntactically valid mermaid diagrams for product documents.
When to Use
Creating mermaid diagrams for PRDs, specs, roadmaps, or stakeholder presentations
Choosing which of 15 diagram types fits a specific communication need
Debugging mermaid code that won't render or renders incorrectly
Reviewing diagrams for clarity, accuracy, and accessibility
When NOT to Use
Exporting diagrams to image files (PNG/SVG) - that's a rendering tool concern
Using non-mermaid diagramming tools (Figma, Lucidchart, draw.io)
Creating purely decorative visuals with no informational purpose
Producing a full customer-journey artifact (stages, touchpoints, emotional curve, pain points) rather than a standalone diagram - use discover-journey-map, which composes this skill for its timeline or flowchart section
The Cardinal Rule
Don't diagram what a list can say.
Diagrams earn their place when they reveal relationships, branching, or flow that prose flattens. Before creating any diagram, ask:
Does this show branching, relationships, or flow that a list or table would flatten?
Yes → proceed with a diagram
No → use a numbered list, bullet list, or table instead
A 5-step linear process is a list. A 5-step process with two decision points and a retry loop is a diagram.