---
title: llm-echo 0.5
link: https://simonwillison.net/2026/Oct/18/llm-echo/
source: simonwillison-net
published: 2026-10-18T23:16:16Z
updated: 2026-10-18T23:16:16Z
first_seen: 2026-10-19T01:05:33.800883674Z
labels:
- llm
summary: 'Release: llm-echo 0.5 I''m working towards a new LLM release, and testing PRs caused me to revisit the llm-echo debug plugin. This plugin provides a "model" which doesn''t involve an LLM at all - it just repeats back the prompts that have been fed to it. The new release now updates the simulated token usage counts to take tool calls, system prompts, and reasoning tokens into account. Example usage: uvx --with llm-echo llm -m echo ''hi there'' -o thinking 1 --usage Outputs: First I consider the prompt, then I decide what to say. { "prompt": "hi there", "system": "", "attachments": [], "stream": true, "previous": [] } Token usage: 2 input, 24 output Tags: llm'
content: extracted
html: 2026-10-18-llm-echo-0-5.html
---

I'm working towards a new [LLM](https://llm.datasette.io/) release, and testing PRs caused me to revisit the `llm-echo` debug plugin. This plugin provides a "model" which doesn't involve an LLM at all - it just repeats back the prompts that have been fed to it. The new release now updates the simulated token usage counts to take tool calls, system prompts, and reasoning tokens into account.

Example usage:

```
uvx --with llm-echo llm -m echo 'hi there' -o thinking 1 --usage
```

Outputs:

```
First I consider the prompt, then I decide what to say.
{
  "prompt": "hi there",
  "system": "",
  "attachments": [],
  "stream": true,
  "previous": []
}
Token usage: 2 input, 24 output
```