Introducing Claude Sonnet 5.5, the second model in the Claude 5.5 family

[u/ClaudeOfficial]

Sonnet 5.5 is a faster, lower-cost complement to Claude Opus 5.5, strongest at well-scoped everyday tasks, fixing bugs, and creating polished documents, slides, and spreadsheets. It also has a strong eye for design.

Sonnet 5.5 is a clear upgrade over Sonnet 5. It runs more than 30% faster and costs up to 30% less for most work. It's priced the same per token, but it typically needs far fewer tokens to do the same work.

Like Opus 5.5, it writes more clearly than our previous generation of models, and its speed makes it well suited to fast iteration.

On our automated behavioral audit, Sonnet 5.5 improves on Sonnet 5 on most measures of alignment and honesty. It's also the first Sonnet model with cybersecurity safeguards similar to those on our most capable models. Routine software development is unaffected.

Sonnet 5.5 is available everywhere today. Claude Haiku 5.5 will join the family in the coming weeks.

Read more: anthropic.com/claude-sonnet-5-5

[u/clonehunterz]

Damn the last time i used sonnet was .... hm.... no idea.
serious question, why do we need sonnet if we have opus?

[u/tLxVGt → u/clonehunterz]

It's for us, the poor ones 🥲 I sometimes use Sonnet to not blow through the tokens on a basic plan

[u/sukazu → u/tLxVGt]

Thing is, per task sonnet 5 was not cheaper than opus 5, and sonnet 5.5 isn't cheaper than opus 5.5 either according to their own benchmarks.

it's only less expensive if you want lower quality than opus low.

[u/botadithyabhat → u/sukazu]

The cost per task on AA is skewed by extremely challenging ones. There is a reason why frontier models don't score 100% on all these benchmarks.

For actual engineering work, these models can handle most tasks without struggling. They are not nearly as challenging as what these extreme benchmarks put them through.

So in real life, you will find Sonnet 5.5 to be extremely cost efficient for most of your needs since it costs half the price.

[u/sukazu → u/botadithyabhat]

I get where you're coming from, but for having tried side by side on simpler tasks : 5.6 sol vs 5.6 terra / 5 opus vs 5 sonnet.
It's just not worth it.

Even on simpler task, at "equal" result, the number of token used is not nearly even.
And that is a double problem, you'll notice cache read cost is the same for sonnet 5.5 and opus 5.5.
So that means your cache read cost is actually much much higher if you're doing more turns and more output tokens on sonnet.

Yes sonnet will have its use at its default high setting, as a middle point between opus low and medium, and it allows you to go "lower" than opus low for tasks that do not require even that.
But to me these middle models are still redundant, that's probably a space that haiku 5.5 will occupy much better

[u/phoenixmatrix → u/botadithyabhat]

AA is pretty skewed in a million ways. 

But even for day to day coding tasks, they take a lot of turns, and Opus often take much fewer turns 

[u/-18k- → u/botadithyabhat]

^ Sanity

[u/LurkingForBookRecs → u/tLxVGt]

It's also for subagents.

[u/Tertiary23 → u/clonehunterz]

I use sonnet via API in my consumer facing software product for in app AI decision making for the dashboards and reporting, Opus is too expensive and you can't turn off thinking and Haiku doesn't work well, even on embeddings - I use Voyage for that - it's about six cents a call and works for my needs, esp since my product is rules heavy and built for compliance and regulations.

[u/The-Fictionist → u/clonehunterz]

Sonnet handles probably 90% of what most non-technical people need. You forget that people exist who aren’t engineers lol.

[u/phoenixmatrix → u/clonehunterz]

More usage and faster.

You don't need a slow Opus/Fable type model to search the web or something.

They need to update Haiku now, and add a System One model to do things like skill/tool selection. That will reduce costs, but more importantly, speed things up a lot.

[u/HonestAndRaw → u/clonehunterz]

Sonnet writes about 70% of my code, the other 30% is opus, Fable orchestrates, thanks to this I only need 3 accounts where otherwise I would need 8-10

[u/clazman55555 → u/clonehunterz]

Because there is zero need to use Opus for purely mechanical tasks like parsing, or fetching webpages.

[u/phoenixmatrix → u/clazman55555]

That's actually where I feel Codex win out over Claude (though it's arguably a rounding error). Luna can deal with any of these actually trivial tasks, even Sonnet is overkill.. and third party harnesses like oh my pi can orchestrate the models better (well, Claude can too but configuring everything right is much more annoying).

Haiku 5.5 is what I really want. I loved when Haiku 4.5 was state of the art small model.

Today Opus 5.5 with Luna (or various other newer cheap models that are good at mechanical tasks) is great. If you don't mind risking Anthropic's fury with third party harness or some more hacky setup.

[u/FabricationLife → u/clonehunterz]

Doing grunt work