Simon Willison’s Weblog

31st March 2026

Release llm-echo 0.3 — Debug plugin for LLM providing an echo model

Mechanisms for testing tool calls. #3

Mechanism for testing raw responses. #4

New echo-needs-key model for testing model key logic. #7

Posted 31st March 2026 at 3:43 pm

Recent articles

Changes in the system prompt between Claude Opus 4.6 and 4.7 - 18th April 2026
Join us at PyCon US 2026 in Long Beach - we have new AI and security tracks this year - 17th April 2026
Qwen3.6-35B-A3B on my laptop drew me a better pelican than Claude Opus 4.7 - 16th April 2026

This is a beat by Simon Willison, posted on 31st March 2026.

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