Prompting Claude Opus 5.5
This guide outlines the behavioral changes and prompting patterns for the new Claude Opus 5.5 model. It emphasizes adjusting 'effort' settings to balance intelligence, latency, and cost, noting that the model is faster and more efficient than its predecessor.
Why it matters
Optimizing prompts for new AI models is essential for developers to maintain performance while managing operational costs.
Behavioral differences from Claude Opus 5 and the prompting and harness patterns that address them: effort calibration, thinking behavior in API integrations and chat, progress updates, unattended and multiagent tasks, safeguard refusals, frontend design, complex visual inputs, multi-app workflows, and pasted text in user messages.
This guide covers the prompting patterns specific to Claude Opus 5.5. For the model's capabilities and API changes, see What's new in Claude Opus 5.5 . For techniques that apply across all current Claude models, see Prompting best practices .
Claude Opus 5.5 generates output tokens more than 30 percent faster than Claude Opus 5 and tends to finish the same task with fewer tokens. Existing Claude Opus 5 prompts should perform well without changes, and the patterns in Prompting Claude Opus 5 remain a reasonable starting point. Start with the section that matches what you observe:
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