Code Explainer Skill
Make unfamiliar code understandable — fast — without dumbing it down.
Working from a brief
Infer the language and intent from the code itself; label assumptions (assumed — confirm). Always produce a complete explanation even from a fragment. Match depth to the apparent level of the question.
Input
Ask for these if not provided:
- The code — the snippet or file to explain (paste it, or point at the path)
- The language or runtime — if it is not obvious from the code
- The reader — who this is for and how much they already know
- What they are trying to understand — the bug, the review, the handover; infer the rest
Output Structure
In one line
What this code does, in a single sentence a busy reader can repeat.
Step by step
A walkthrough of the logic in order — group by block/function. Explain why, not just what, for anything non-trivial. Reference line ranges where helpful.
Worth knowing
The non-obvious bits: clever tricks, gotchas, side effects, complexity, dependencies, or assumptions the code makes.
Anything off?
Bugs, edge cases, or smells you noticed while reading — with the fix. (If it's clean, say so.)
Quality Checks
- The one-line summary stands alone
- The walkthrough explains why, not just restating the code in words
- Non-obvious behaviour (side effects, complexity, edge cases) is surfaced
- Any bug/smell spotted is flagged with a fix
Anti-Patterns
- Do not narrate line-by-line in English ("this line sets x to 5") — explain intent and structure
- Do not skip the gotchas — the value is in the non-obvious parts
- Do not assume expert level if the question reads like a beginner's (or vice-versa)
- Do not ignore a bug you can see just because you weren't asked to review it