---
title: "llm-coding-agent 0.1a0 Released: A Simple Coding Agent Built on LLM"
source: "Simon Willison 博客（Atom）"
source_tier: "t2"
url: "https://simonwillison.net/2026/Jul/2/llm-coding-agent/#atom-everything"
permalink: "https://feed.astralor.com/items/itm_304f4fc74033b4d43b6f7973"
published: "2026-07-02T19:33:12.000Z"
score: 68
channel: "ai"
tags: ["LLM","llm-coding-agent","Python","coding-agents"]
---

# llm-coding-agent 0.1a0 Released: A Simple Coding Agent Built on LLM

## At a glance

Simon Willison released llm-coding-agent 0.1a0, an experimental coding agent built on top of his LLM library which has evolved into an agent framework. The tool implements Claude Code-like capabilities with tools for file editing, command execution, file searching, and more, developed using TDD. It is now available on PyPI and can be run directly via the uvx command. The project supports various modes such as --yolo and --allow parameters, and also provides a Python API for integration.

## Key points

- Built on the evolved LLM agent framework, implementing a simple coding agent
- Includes 6 tools: edit_file, execute_command, list_files, read_file, search_files, write_file
- Supports --yolo and --allow parameters, plus a Python API
- Developed using red/green TDD, published to PyPI

## Full text

Release: llm-coding-agent 0.1a0 Another Fable 5 experiment. Now that my LLM library has evolved into more of an agent framework it's time to see what a simple coding agent would look like built on it. I started a new Python library using my python-lib-template-repository GitHub template repository, then ran these two prompts (here's the Claude Code for web transcript): Write a spec.md for this project - it will depend on the latest “llm” alpha from PyPI and implement a Claude code style coding agent complete with tools for reading and editing files and executing commands Then: Commit the spec, then build it using red/green TDD in a series of sensible commits (each with passing tests and updated docs) - occasionally manually test it using the OpenAI API key in your environment Here's the resulting README file and the sequence of commits. I've shipped a slop-alpha to PyPI, so you can run the new agent like this: uvx --prerelease=allow --with llm-coding-agent llm code It's pretty good for a first attempt! Here's the (Fable-authored) README, which lists recipes like llm code --yolo and llm code --allow "pytest*" --allow "git diff*". It also presents a Python API based around a CodingAgent(model="gpt-5.5", root="/path", approve=True).run("Fix the failing test in tests/test_parser.py") class which I didn't ask for but I'm delighted to see implemented. Here's the suite of tools it implemented, listed using uvx ... llm tools: CodingTools_edit_file(path: str, old_string: str, new_string: str, replace_all: bool = False) -> str Replace an exact string in a file. old_string must match the file contents exactly (including whitespace) and must identify a unique location unless replace_all is true. Returns a diff of the change so it can be verified. CodingTools_execute_command(command: str, timeout: int = 120) -> str Run a shell command in the session root directory. Returns combined stdout and stderr followed by an Exit code line. timeout is in seconds (maximum 600); on timeout the whole process tree is killed. CodingTools_list_files(pattern: str = '**/*', path: str = '.') -> str List files matching a glob pattern, newest first. Skips hidden directories, node_modules, __pycache__ and (in a git repository) anything covered by .gitignore. Returns at most 200 paths relative to the searched directory. CodingTools_read_file(path: str, offset: int = 0, limit: int = 2000) -> str Read a text file, returning numbered lines like cat -n. Paths are relative to the session root. Use offset (0-based first line) and limit (max lines) to page through files too large to read in one call. CodingTools_search_files(pattern: str, path: str = '.', glob: str = None, max_results: int = 100) -> str Search file contents for a regular expression. Returns matches as path:line_number:line, capped at max_results. Use glob (e.g. "*.py") to restrict which files are searched. CodingTools_write_file(path: str, content: str) -> str Create or overwrite a file with the given content. Parent directories are created as needed. Prefer edit_file for modifying existing files. Tags: projects, ai, generative-ai, llm, llm-tool-use, coding-agents, claude-code, claude-mythos

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