I tried Claude Opus 5.5 which became available for selection in Kiro
This page has been translated by machine translation. View original
Introduction
On September 28, 2026, Claude Opus 5.5 became available as an Experimental preview in Kiro with an enterprise license.
This article introduces the behavior we were able to confirm in Kiro IDE / CLI.
Overview of Claude Opus 5.5
According to Anthropic's announcement, Opus 5.5 is said to perform on par with Fable 5.1 for many tasks.
The API pricing is $4 for Input / $20 for Output (per 1 million tokens), which is 20% cheaper than Opus 5.
Verification Environment
Verified with Kiro CLI 2.24.1 (Linux aarch64).
Model Selection in Kiro IDE
In Kiro IDE, clicking the model selector at the bottom of the screen (shown as "Auto" in the image, at the arrow position) opens the model selector. Claude Opus 5.5 appears in the list as an Experimental preview. The context is 1M and the credit multiplier is 2x. Both Opus 5 and Opus 4.8 are at 2.2x.
Model Selection in Kiro CLI
In Kiro CLI, use /model to switch models. claude-opus-5.5 is 2.00x credits, the same as in the IDE. This is a lower multiplier than the 2.20x for claude-opus-5 and claude-opus-4.8 listed alongside it.
› /model
Select model: type to search
❯ auto 1.00x credits Models chosen by task for optimal usage and consistent quality
claude-opus-5.5 2.00x credits Experimental preview of Claude Opus 5.5 model with 1M context window [active]
claude-opus-5 2.20x credits Claude Opus 5 model with 1M context window
claude-sonnet-5 1.30x credits Claude Sonnet 5 model with 1M context window
claude-opus-4.8 2.20x credits Claude Opus 4.8 model with 1M context window
gpt-5.6-sol 4.40x credits Experimental preview of OpenAI GPT 5.6 Sol with 1M context window
gpt-5.6-terra 2.20x credits Experimental preview of OpenAI GPT 5.6 Terra with 1M context window
gpt-5.6-luna 1.10x credits Experimental preview of OpenAI GPT 5.6 Luna with 1M context window
The reduction in the multiplier is approximately 9%. This is a smaller change compared to the 20% decrease in Anthropic API Input/Output unit price relative to Opus 5.
Model Selection in Kiro Model Governance
For this account, model governance had been enabled to use Fable 5.1. In this state, after checking Opus 5.5 in the admin screen, Opus 5.5 was added to the model selection in CLI and IDE. If Opus 5.5 does not appear as an option, please also check your model governance settings.
From "Model Availability" in the admin screen settings, open "Manage Approved List."
Check the box for Claude Opus 5.5 in the list of available models.
Summary
Claude Opus 5.5 is now selectable in Kiro as well.
The following comment has been received from Kiro regarding the announcement of Opus 5.5.
"Every call an agent makes is time and cost a developer feels. On a public benchmark of real command-line tasks, Claude Opus 5.5 solved more than Opus 5 while making about 40% fewer calls and using half the tokens. For developers building with Kiro, that means faster, more affordable agent sessions for routine tasks and complex challenges alike. Opus 5.5 will soon be available in Kiro."
— Deepak Singh, VP of Agentic AI, Kiro (Introducing Claude Opus 5.5)
We plan to evaluate the performance improvement of approximately 40% fewer calls and half the token usage going forward.
If Opus 5.5 appears in your list of available models in Kiro, please give it a try.
