One signal

Update

What changed

The llm-anthropic 0.29 release adds support for Claude Opus 5.5, allowing users of Simon Willison’s llm command-line tool to call the model with llm -m claude-opus-5.5. That turns Anthropic’s model announcement into a concrete developer workflow, rather than leaving Opus 5.5 parked on a pricing page waiting for someone to wire it in.

The change is modest but useful: people already using llm can select Claude Opus 5.5 directly from the command line and send it a prompt. The supplied release note does not give benchmark results, latency figures, rate limits or any evidence that the model performs better than alternatives, so this is an integration update rather than a fresh capability claim.

For developers comparing model costs and behaviour, the practical next step is to test Opus 5.5 in the same workflows they use for other models. Anthropic’s lower reported pricing matters more once the model is available through familiar tooling, although the bill will still depend on token use and the work being attempted.

Sources and evidence

• llm-anthropic 0.29: Simon Willison reports that llm-anthropic 0.29 adds support for Claude Opus 5.5, including the claude-opus-5.5 model identifier for command-line use.

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