Simplify and code review (skills)

Simplify is Anthropic's official skill for reviewing changed code for reuse, quality and efficiency and then applying the fixes; community code-reviewer skills do the same job with a checklist flavour.^[1] The point is timing: the review runs before the agent presents its work, so the output is already revised.

What it looks for

Logic that could be a shared utility, functions doing more than one thing, patterns inconsistent with the rest of the codebase, unnecessary re-renders and N+1 queries, dead code and unused imports, names that do not say what they mean. It rewrites rather than reports.

How to get the most from it

Write the project's standards into its agent instructions file: a line limit for functions, how many repeats justify extracting a helper, the types that may not be loosened, what every async call must handle. The review pass reads those and checks for them.^[2] The article's own example is two near-identical fetch functions becoming one helper with error handling.

Things to know

• It is not a bug hunt. A separate correctness review is still worth running on anything risky.
• Complexity that is there for a reason needs a comment saying so, or the pass will remove it.

History

• 2026-10-09: article written and published.
• 2026-10-09: entry created.