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points by Silagi 3 days ago | 0 comments

Can anyone give me the compelling reason for Terra and Sonnet to exist?

Virtually every task I give to either is better served by going up a tier and down a reasoning level, or down a tier and up a reasoning level. I simply don't understand their use case. No testing I've done has shown them to have a niche where there isn't a cheaper-with-equal-results or more-performant-at-same-cost option.

[–] h14h 3 days ago

I think for the majority of the audience here who use these models inside of coding agent harnesses w/ subsidized monthly subscriptions, there likely isn't one. Depending on how Terra contributes to the rate limits, it may make sense to use it for some subset of a repeated workflow to get more mileage out of sub.

If you pay API prices for inference in your product stack & have specific use-cases w/ custom evals, these smaller models provide an additional cost/speed lever to adjust. Ultimately, I think the point is to compete on cost for use-cases where Sol on the lowest reasoning is overkill.

If you have a fairly straightforward usecase where Terra performs just as well as Sol, but is faster and cheaper, why not use it?

[–] daynthelife 3 days ago

The real issue with coding harnesses is that you get a cache miss any time you switch models. I might have some easy task (e.g. "fix lints") that I could delegate to Terra, because my session has been using Sol up to this point, I'd pay a full uncached prefill if I routed it to Terra. It ends up being cheaper in practice to just stick with Sol.

Spinning up a fresh session would be a reasonable choice in the above case, but sometimes you still need the retained context.

[–] fy20 3 days ago

Yes but you are missing the point. It's the case where Luna is not good enough, and Sol is too much. The problem is that on benchmarks Luna xhigh is typically comparable to Sol low in terms of capability. So where does Terra fit in?

[–] h14h 2 days ago

Speed.

Terra 6.1 on low reasoning outperforms Luna 6 on max reasoning, while costing half as much per task and completing each task over 10x faster (per AA v5).

Luna 6.1 will likely close the intelligence & cost gaps, but that speed advantage will remain.

[–] dannyw 3 days ago

World knowledge, factual recall without grounding, more complex instruction following, etc.

Benchmarks don’t really tell you much. For API best will always be a model+effort sweep on your internal evals (and if you don’t have internal evals, do that first).

For individual coding harnesses, honestly I just go with vibes. The best workflow is the one that works for you.

[–] foretop_yardarm 3 days ago

Idk… I’ve written 100k sloc in ~2 weeks on the Claude £20 subscription with sonnet medium alone. Seems pretty good to me.

[–] selcuka 3 days ago

I guess the question is whether you could have done the same using Haiku High/XHigh or Opus Low/Medium at roughly the same speed and cost.

[–] eknkc 3 days ago

On the API we use a lot of Luna (cost efficient) and sometimes Terra level models. I think we never use a larger model. These are models that our app runtimes depend on.

On subscription for coding and stuff I am basically on Astra Ultra all day long.

[–] legulere 3 days ago

They are the biggest models supported in Github Copilot Pro

https://docs.github.com/en/copilot/reference/ai-models/suppo...

[–] onlyj 3 days ago

You should look at model reasoning level curves on the cost/performance chart on artificial analysis. If you compare the curves for haiku/sonnet/opus I would agree with you that sonnet serves no purpose because it is priced too high. If you look at luna/terra/sol you will see that terra is priced such that it successfully fills a gap between luna and sol. And when you add speed into the equation it adds another dimension where terra makes sense. terra low falls between luna xhigh and max on both cost and intelligence, but it is way faster because it uses way fewer reasoning tokens. So I would say there are workloads where terra makes sense. But from my analysis I don't see any workloads where sonnet makes sense.

[–] nfw2 3 days ago

There is a chasm of performance difference between haiku and sonnet ime. Sonnet is cheaper and faster than Opus, so if you're providing a service via api where cost and speed is important, it's a big difference.

[–] datadrivenangel 3 days ago

Except Sonnet is slower, more expensive, and worse at reasoning levels above ~medium. Opus on low is faster, cheaper, and better at doing things.

[–] nfw2 3 days ago

1. In Anthropic's benchmarks, Opus's advantage over Sonnet diminishes at high reasoning levels. Sonnet max actually beats Opus max.

2. There are rote or simple tasks where higher reasoning isn't needed and one model vs the other wouldn't even be distinguishable.

3. How many tokens are used during reasoning depends as much on the task as the reasoning level.

4. Sonnet is faster and half the price per token, so Opus will only be cheaper if it can spend fewer tokens. This won't be the case for all tasks. Opus and Sonnet will also consume the same number of tokens to load context, so the relative price comparison depends a lot on where the task is context-heavy or reasoning-heavy.

[–] datadrivenangel 3 days ago

> Sonnet max actually beats Opus max.

What are you smoking and can I have some?

[–] nfw2 2 days ago

I am telling what's on Anthropic's official announcement. It's not a subjective assessment.

[–] moecables 3 days ago

Sonnet is way faster than Opus when doing everyday tasks, I think on the subscription plans it's a better option when you need something done faster than Opus' long thinking sessions.

[–] hobofan 3 days ago

For coding, no.

I have some business automation process for some customers that I maintain, where Terra with low reasoning ended up with the best price/performance & latency. With an equivalent Luna with high reasoning, price was usually better, but quality had a higher variance (very much depends on where the thinking takes the model) and latency for high reasoning was worse.

[–] rfgplk 3 days ago

Cheap and affordable. Dispatching proper tasks to these models can save you a huge % of your quota. Especially if you _know_ the task is simple (ie add something here or there, or archive a bunch of files and reformat kinda thing)

[–] Silagi 3 days ago

Maybe it's my tasks, but in the cases you're describing, I'm usually better off going down to Luna. I specifically don't see the gap where "It's too complex for Luna-high" and "It's not complex enough for Sol-low" exists.

[–] rfgplk 3 days ago

I've personally found that most models completely collapse at sub-medium effort. I generally run most of my stuff at medium/xhigh with heavy core tasks @ max

[–] InsideOutSanta 3 days ago

If you trust these benchmarks, I'd argue that there's almost never a reason to use anything other than Terra 6.1 xhigh.

[–] qert12 3 days ago

> Can anyone give me the compelling reason for Terra and Sonnet to exist?

To justify the pricing of Sol and Astra. Old business trick.

[–] jhatemyjob 3 days ago

This is the only reason that makes sense to me. Thank you

[–] handzhiev 3 days ago

If you use API in agent or your own integration with software, such models make a lot of sense. We use Terra 5.6 for "question to SQL" translation for example. It's good enough and affordable enough. Luna will probably not handle complex queries well while Sol is too expensive.

[–] notatoad 3 days ago

i use sonnet to generate answers to help-desk tickets, which it does for significantly cheaper and insignificantly worse than opus.

if you're just talking about use in codex or claude code, then sure, leave it on opus all the time. but for running routine api requests, sonnet is great.

[–] datadrivenangel 3 days ago

Sometimes this tier is faster, and getting a good enough result in a few seconds instead of a better result in ~15-30 seconds is a meaningful result.

I think it's also a fake lever to give to finops / it teams to try and keep costs down.

[–] Sha1rholder 3 days ago

https://news.ycombinator.com/item?id=50248124#50249160

Take a look at this reply.

[–] altcognito 3 days ago

I've been refused to do cybersecurity (read-only investigative access against the recent brotli cve) with Opus 5.5 when I had full SSH access, so I guess you've got to have a fallback?

[–] r0fl 3 days ago

I cannot figure it out either. I use Astra Ultra to plan and 6.1Sol High or X-High to build and even on huge projects with 10s of 1000s of pages it is fast and competent

[–] rattynm 3 days ago

I'm on Claude's default plan for personal use, and Sonnet is plenty enough for small projects while not hitting my usage limits too hard.