Notes and two pelicans: https://simonwillison.net/2025/Nov/24/claude-opus/
:%s/There model/Their model/g
Claude Opus 4.5
211–220 of 525 posts
Re: Claude Opus 4.5
#212I wish it was open-weights so we could discuss the architectural changes. This model is about twice as fast as 4.1, ~60t/s Vs ~30t/s. Is it half the parameters, or a new INT4 linear sparse-moe architecture?
Re: Claude Opus 4.5
#213What causes the improvements in new AI models recently? Is it just more training, or is it new, innovative techniques?
Some months back they changed their terms of service and by default users now allow Anthropic to use prompts for learning. As it's difficult to know if your prompts, or derivations of it, are part of a model, I would consider the possibility that they use everyone's prompt.
Re: Claude Opus 4.5
#214They lowered the price because this is a massive land grab and is basically winner take all.
I love that Antrhopic is focused on coding. I've found their models to be significantly better at producing code similar to what I would write, meaning it's easy to debug and grok.
Gemini does weird stuff and while Codex is good, I prefer Sonnet 4.5 and Claude code.
Re: Claude Opus 4.5
#215Earlier quoted context omitted.
> The nerf is psychologial, not actual Once I tested this, I gave the same task for a model after the release and a couple weeks later. In the first attempt it produced a well-written code that worked beautifully, I started to worry about the jobs of the software engineers. Second attempt was a nightmare, like a butcher acting as a junior developer performing a surgery on a horse. Is this empirical evidence? And this…
No, it's entirely psychological. Users are not reliable model evaluators. It's a lesson the industry will, I'm afraid, have to learn and relearn over and over again.
Giving the same prompt resulting in totally different results is not user evaluation. Nor psychological. You cannot tell the customer you are working for as a developer, that hey, first time it did what you asked, second time it ruined everything, but look, here is the benchmark from Antrophic, according to this there is nothing wrong.
The only thing that matters and that can evaluate performance is the end result.
But hey, the solution is easy: Antrophic can release their own benchmarks, so everyone can test their models any time. Why they don’t do it?
Re: Claude Opus 4.5
#216The burying of the lede here is insane. $5/$25 per MTok is a 3x price drop from Opus 4. At that price point, Opus stops being "the model you use for important things" and becomes actually viable for production workloads. Also notable: they're claiming SOTA prompt injection resistance. The industry has largely given up on solving this problem through training alone, so if the numbers in the system card hold up under a…
This is also super relevant for everyone who had ditched Claude Code due to limits: > For Claude and Claude Code users with access to Opus 4.5, we’ve removed Opus-specific caps. For Max and Team Premium users, we’ve increased overall usage limits, meaning you’ll have roughly the same number of Opus tokens as you previously had with Sonnet. We’re updating usage limits to make sure you’re able to use Opus 4.5 for daily…
Interesting. I totally stopped using opus on my max subscription because it was eating 40% of my week quota in less than 2h
Re: Claude Opus 4.5
#217Does anyone know or have a guess on the size of this latest thinking models and what hardware they use to run inference? As in how much memory and what quantization it uses and if it's "theoretically" possible to run it on something like Mac Studio M3 Ultra with 512GB RAM. Just curious from theoretical perspective.
Rough ballpark estimate:
- Amazon Bedrock serves Claude Opus 4.5 at 57.37 tokens per second: https://openrouter.ai/anthropic/claude-opus-4.5
- Amazon Bedrock serves gpt-oss-120b at 1748 tokens per second: https://openrouter.ai/openai/gpt-oss-120b
- gpt-oss-120b has 5.1B active parameters at approximately 4 bits per parameter: https://huggingface.co/openai/gpt-oss-120b
To generate one token, all active parameters must pass from memory to the processor (disregarding tricks like speculative decoding)
Multiplying 1748 tokens per second with the 5.1B parameters and 4 bits per parameter gives us a memory bandwidth of 4457 GB/sec (probably more, since small models are more difficult to optimize).
If we divide the memory bandwidth by the 57.37 tokens per second for Claude Opus 4.5, we get about 80 GB of active parameters.
With speculative decoding, the numbers might change by maybe a factor of two or so. One could test this by measuring whether it is faster to generate predictable text.
Of course, this does not tell us anything about the number of total parameters. The ratio of total parameters to active parameters can vary wildly from around 10 to over 30:
120 : 5.1 for gpt-oss-120b
30 : 3 for Qwen3-30B-A3B
1000 : 32 for Kimi K2
671 : 37 for DeepSeek V3
But you can fit a 3 bit quantization of Kimi K2 Thinking, which is also a great model. HuggingFace has a nice table of quantization vs required memory https://huggingface.co/unsloth/Kimi-K2-Thinking-GGUF
Re: Claude Opus 4.5
#218Earlier quoted context omitted.
it's not about the terminal, but about decoupling yourself from looking at the code. The Claude app lets you interact with a github repo from your phone.
Interesting. Tell me more.
https://apps.apple.com/us/app/claude-by-anthropic/id64737536...
Has a section for code. You link it to your GitHub, and it will generate code for you when you get on the bus so there's stuff for you to review after you get to the office.
Re: Claude Opus 4.5
#219that chart at the start is egregious
Feels like a tongue-in-cheek jab at the GPT-5 announcement chart.
Re: Claude Opus 4.5
#220The burying of the lede here is insane. $5/$25 per MTok is a 3x price drop from Opus 4. At that price point, Opus stops being "the model you use for important things" and becomes actually viable for production workloads. Also notable: they're claiming SOTA prompt injection resistance. The industry has largely given up on solving this problem through training alone, so if the numbers in the system card hold up under a…
This is also super relevant for everyone who had ditched Claude Code due to limits: > For Claude and Claude Code users with access to Opus 4.5, we’ve removed Opus-specific caps. For Max and Team Premium users, we’ve increased overall usage limits, meaning you’ll have roughly the same number of Opus tokens as you previously had with Sonnet. We’re updating usage limits to make sure you’re able to use Opus 4.5 for daily…
I like that for this brief moment we actually have a competitive market working in favor of consumers. I ditched my Claude subscription in favor of Gemini just last week. It won't be great when we enter the cartel equilibrium.