AI Weekly Malaysia

Anthropic's docs page for prompting Claude Opus 5.5 describes behavioral differences from Opus 5 and gives harness patterns for them. The one hard number in the text: Opus 5.5 generates output tokens more than 30 percent faster than Opus 5 and tends to finish the same task with fewer tokens, and existing Opus 5 prompts are said to work unchanged. The page is organized as a symptom index (effort calibration, thinking-disabled prompts, unattended agents that stall after reporting progress, stop_reason "refusal", silent long agentic turns, multi-app context, multiagent time signals, pasted text being followed as instructions, complex visual inputs, generic frontend output) and points to a separate migration guide for four breaking API changes from Opus 5. The excerpt is cut off before the actual capability details and before those four breaking changes are listed.

Why: If you already ship on Claude Opus 5, the two things that force action are the four breaking API changes and the documented failure modes: agents that stop partway after a progress update, silent long agentic turns, and stop_reason "refusal" responses all have named fixes here rather than guesswork. The 30 percent faster output tokens and fewer tokens per task is the only cost/latency claim in the text, so treat it as a reason to re-measure your own token spend after swapping the model ID, not as a reason to swap blindly. Because the excerpt is truncated, you cannot see the four breaking changes or the effort-calibration guidance from this text alone - open the migration guide before changing anything.