One clear task
A skill handles one job well, like CDC lint or timing-path analysis.
Use a skill when you want one report or one planning output.
Simple guide
A skill is a tool. A rule is a guardrail. A flow is a recipe.
If you only remember one thing, remember this: the repo breaks a hard engineering problem into small parts so the AI can stay focused, grounded, and easier to trust.
One shared constraint
A rule tells the AI what it must prove, what it must not invent, or how the result must look.
Use rules when the same engineering discipline should apply everywhere.
One bigger workflow
A flow runs several skills in order so a larger task can finish cleanly.
Use a flow when one answer needs many steps, not one quick check.
Quick decision guide
Use the page below like a routing table.
"Can you check this RTL for CDC problems?"
Best fit: a skill.
Why: this is one focused task with one report.
"Please do not guess when the RTL is unclear."
Best fit: a rule.
Why: this safety behavior should be reused in many tasks.
"Build a full DV plan for this block."
Best fit: a flow.
Why: the answer needs objectives, surface extraction, tests, assertions, coverage, and one final plan.
"Which UVM pieces do I really need?"
Best fit: a skill that also uses rules.
Why: the planner chooses the smallest justified environment instead of adding pieces "just in case."