Codecrafters Claude Code Python — AI skill for Claude Code

[](https://app.codecrafters.io/users/BuildWithAbid?r=2qF)

Build Your Own Claude Code in Python — a minimal LLM coding agent from scratch

An **LLM-powered coding agent** in ~280 lines of Python. Give it a prompt, and it decides which tools to call (Read, Write, Edit, Bash, Glob, Grep), actually runs them on your filesystem, feeds the results back to the model, and keeps looping until the task is done. The tool surface mirrors the real [Claude Code](https://claude.com/claude-code) CLI.

Built in under **48 hours** with Claude Code itself, while reaching **CodeCrafters Python leaderboard rank #13**.

If you searched for *"build an LLM agent from scratch"*, *"OpenAI tool calling Python"*, *"AI coding assistant implementation"*, or *"agent loop tutorial"* — this repo is a compact, readable starting point.

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What it does

export OPENROUTER_API_KEY=...
./your_program.sh -p "Summarize what app/main.py does and propose 2 refactors."

The agent will:

1. Call Read on app/main.py
2. Think about the content
3. Possibly call Grep or Glob to explore the project
4. Produce its final answer

Or:

./your_program.sh -p "Add a --verbose flag to app/main.py that prints each tool call."

And it will edit the file in place with **Edit** — because the model chose to.

Implemented tools (match the real Claude Code)

Tool	Purpose
Read	Return the contents of a file
Write	Write content to a file (overwrite)
Edit	Exact string replace with uniqueness / replace_all checks
Bash	Run a shell command, return stdout/stderr/exit code
Glob	Find files by glob pattern, sorted by mtime
Grep