llm-echo 0.5a0

Simon Willison's Blog Tools
llm echo plugin debug testing open-source release

Summary

llm-echo 0.5a0 release adds a -o thinking 1 option to help test against LLM 0.32a0 and higher. This plugin provides a fake echo model for automated testing.

No content available
Original Article
View Cached Full Text

Cached at: 05/08/26, 06:34 AM

# Release: llm-echo 0.5a0 Source: [https://simonwillison.net/2026/May/5/llm-echo/](https://simonwillison.net/2026/May/5/llm-echo/) 5th May 2026 Release[llm\-echo 0\.5a0](https://github.com/simonw/llm-echo/releases/tag/0.5a0)— Debug plugin for LLM providing an echo model > - New`\-o thinking 1`option to help test against[LLM 0\.32a0](https://llm.datasette.io/en/latest/changelog.html#a0-2026-04-28)and higher\. This plugin provides a fake model called "echo" for LLM which doesn't run an LLM at all \- it's useful for writing automated tests\. You can now do this: ``` uvx --with llm==0.32a1 --with llm-echo==0.5a0 llm -m echo hi -o thinking 1 ``` This will fake a reasoning block to standard error before returning JSON echoing the prompt\. Posted[5th May 2026](https://simonwillison.net/2026/May/5/)at 1:31 am ## Recent articles - [Notes on the xAI/Anthropic data center deal](https://simonwillison.net/2026/May/7/xai-anthropic/)\- 7th May 2026 - [Live blog: Code w/ Claude 2026](https://simonwillison.net/2026/May/6/code-w-claude-2026/)\- 6th May 2026 - [Vibe coding and agentic engineering are getting closer than I'd like](https://simonwillison.net/2026/May/6/vibe-coding-and-agentic-engineering/)\- 6th May 2026 This is a**beat**by Simon Willison, posted on[5th May 2026](https://simonwillison.net/2026/May/5/)\. [llm596](https://simonwillison.net/tags/llm/) ### Monthly briefing Sponsor me for**$10/month**and get a curated email digest of the month's most important LLM developments\. Pay me to send you less\! [Sponsor & subscribe](https://github.com/sponsors/simonw/)

Similar Articles

llm 0.32a3

Simon Willison's Blog

Release of llm 0.32a3, an alpha version of Simon Willison's command-line tool for interacting with large language models.

llm 0.32a0

Simon Willison's Blog

This article announces the release of version 0.32a0 of the 'llm' command-line tool by Simon Willison, providing a monthly briefing on LLM developments.

llm-anthropic 0.25

Simon Willison's Blog

llm-anthropic 0.25 releases with support for Claude Opus 4.7, new thinking_effort and thinking_display options, increased default max_tokens, and removal of obsolete beta headers.

llm 0.31.1

Simon Willison's Blog

Release of llm 0.31.1, a command-line tool for interacting with large language models, by Simon Willison.

llm 0.32a2

Simon Willison's Blog

The llm CLI tool version 0.32a2 has been released, adding support for OpenAI's /v1/responses endpoint to enable interleaved reasoning for GPT-5 class models.