choosing-a-model changedabout-claude/models/choosing-a-model
Nearest release: v2.1.292, published 11 hours before this site recorded the change. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.
Recorded here
Lines+1added
Lines−1removed
From line
55
where the diff opens
First seen
14 Aug 2026
this site's first read of the page
Recorded edits14to this page, all time
The whole hunk
from line 55, old and new numbered
/
from line 55
5555
5656**Claude Opus 5.5** (`claude-opus-5-5`) is built for long-running agentic coding and knowledge work, with [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking) always on. If your integration forces tool use (`tool_choice` of type `any` or `tool`), turns thinking off, or uses the `computer_20251124` computer use tool, see [Breaking changes](https://platform.claude.com/docs/en/models/opus-5-5/whats-new-opus-5-5#breaking-changes) before switching.
5757
58**Claude Fable 5.1** (`claude-fable-5-1`) is Anthropic's most capable model open to all customers. It extends Claude Fable 5 with stronger long-running agentic coding, knowledge work, and research at the same input and output prices, with cache reads at a quarter of the cost. **Claude Mythos 5.1** (`claude-mythos-5-1`) offers the same capabilities to [Project Glasswing](https://anthropic.com/glasswing) participants only. Both models use always-on [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking). See [What's new in Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/whats-new-fable-5-1) for details.
58**Claude Fable 5.1** (`claude-fable-5-1`) is Anthropic's most capable model open to all customers. It extends Claude Fable 5 with stronger long-running agentic coding, knowledge work, and research at the same input and output prices, with cache reads at a quarter of the cost. **Claude Mythos 5.1** (`claude-mythos-5-1`) offers the same capabilities only to organizations verified through Anthropic's verification programs, such as the [Cyber Verification Program](https://support.claude.com/en/articles/14604842). Both models use always-on [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking). See [What's new in Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/whats-new-fable-5-1) for details.
5959
6060For context windows, output limits, and prices, see the [model comparison table](https://platform.claude.com/docs/en/models/overview#latest-models-comparison).
6161
No line in this hunk matches that.