Unclear The finding does not say whether Opus 5.5 is an available or announced model, only that its name now appears in this styling code.
What
The model picker's description formatting, which applies special styling and strikes through a promotional price for one particular model, now targets "Opus 5.5" instead of "Fable 5.1", matching a new model ID, claude-opus-5-5, that appears in the system prompt.
Why
This is a UI update reflecting a new model reference, Opus 5.5, showing up in Claude Code's model picker.
Names in the bundleclaude-opus-5-5
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Added since
A small documentation edit on API usage primer for Claude touched a line naming claude-opus-5-5 after this was published.
* Claude Opus 5.5 (`claude-opus-5-5`, adaptive thinking only, always on)claude_api_primer see the edit
Confirmed since
Anthropic's documentation has since written up claude-opus-5-5, on claude-api-skill.
When the scope is ambiguous (for example, a bare `/claude-api migrate to claude-opus-5-5`), the skill asks you to choose between the entire working directory, a specific subdirectory, or an explicit file list before editing any files. This…agents-and-tools/agent-skills/claude-api-skill see the edit
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
The finding does not say whether Opus 5.5 is an available or announced model, only that its name now appears in this styling code.
Anthropic's documentation agrees
Anthropic's documentation has since written up claude-opus-5-5, on claude-api-skill.
Anthropic's release notes agree
Added Claude Opus 5.5 (claude-opus-5-5), now the default Opus model — 1M context, $4/$20 per Mtok with $0.20/Mtok cache reads