How Claude’s Open‑Source Code‑Simplifier Agent Refactors Your JavaScript/TypeScript Code

Installation (official plugin)

Open Claude Code and run the three commands:

/plugin marketplace update claude-plugins-official
/plugin install code-simplifier

System prompt (core logic)

The agent is driven entirely by a system prompt that defines its role, goals, and detailed guidelines. The prompt begins with metadata (name, description, model) and then instructs the AI to act as an expert code‑simplification specialist, preserving functionality while improving clarity, consistency, and maintainability.

Five core principles

Preserve Functionality : never change what the code does, only how it does it.

Apply Project Standards : follow the rules in CLAUDE.md (e.g., mandatory return‑type annotations, ES‑module imports, React component patterns).

Enhance Clarity : eliminate nested ternary operators, prefer explicit if/else or switch, use clear variable and function names, and remove unnecessary comments.

Maintain Balance : avoid over‑simplification that would reduce readability, introduce clever but obscure solutions, or collapse too many concerns into a single function.

Focus Scope : only refactor code that has been recently modified, preventing large‑scale changes that could cause Git conflicts or bugs.

Standardized refactoring workflow

Identify the recently changed files.

Analyze them for opportunities to improve elegance and consistency.

Execute the project‑specific standards.

Verify that all functionality remains unchanged.

Validate that the code is now simpler and more maintainable.

Archive only significant changes for documentation.

Language‑specific pitfalls

The official prompt is tightly coupled to TypeScript, React, and ES modules. Applying it unchanged to Java, Python, or Go projects can introduce conflicts because the language‑specific conventions (e.g., function vs. def, module system) are hard‑coded.

To reuse the logic in other ecosystems, extract the abstract framework (principles, workflow) and replace the concrete conventions with equivalents for the target language.

Community‑maintained adaptation

A customized version of the prompt that abstracts language‑specific parts is available in a public GitHub repository:

https://github.com/chujianyun/claude-plugins-wuming/tree/main

Installation of the adapted plugin uses the same two‑step command sequence:

/plugin marketplace add chujianyun/claude-plugins-wuming
/plugin install code-simplifier

Reference material

The original system prompt can be inspected at:

https://github.com/anthropics/claude-plugins-official/blob/main/plugins/code-simplifier/agents/code-simplifier.md