Claude Sonnet 5 Is Not Frontier But Has Its Uses

Fable 5 is back today, baby! Premium subscribers have one week to use it within their subscriptions. First hit’s free. Then you pay by the token. Today’s post is still about Sonnet 5. I don’t know that there will be much call for Sonnet 5 for most purposes, given Opus 4.8 exists and especially now that Fable 5 is once again available, but this is what we do here, so sure, why not, system card time, including model welfare, after which we’ll do capabilities. Sonnet costs $3/$15 per million tokens, versus $5/$25 for Opus and $10/$50 for Fable, after an introductory period. Once you pay for all the tokens you need you’re not really saving money, such as on the ArtificialAnalysis index where Sonnet ended up being more expensive. My initial impression is that if you want me to use Sonnet over Opus for most purposes, you’re going to have to offer a bigger discount than that. The counterargument is speed. Sonnet 5 is faster without being that much less capable. In many cases, getting into a flow state like that is pretty valuable. There are a few agentic scenarios Sonnet 5 has more robustness than Opus, so you might actively trust it more there. If your tasks are relatively easy and simple then the discount and speed could matter more, and when tasks are easy it seems relatively token efficient. When it is good enough for the job, it is a good choice. Each Anthropic release is unique in various ways. Sonnet 5 seems more unique than usual, likely due to being a Sonnet trained with at least some help from Mythos. Those who are interested in such things have lots to explore. So Sonnet 5 has its uses. It just won’t be a good choice for most people’s daily driver. I don’t expect to use it much, but that could be a me problem. Rapid iteration and exploring strange spaces are valuable, and I definitely don’t do enough low effort AI queries. (Above: Sonnet 5 self-portrait, as implemented by GPT-Image.) Table of Contents Mythos Exists. Introduction (1). RSP Evaluations (2). Cyber (