Where Opus 5.5 fits best
Opus 5.5 is presented as better suited to long, multi-step work that can proceed with limited supervision. Anthropic’s guide recommends putting the full task in one message, defining what “done” means, and specifying when the model should stop to ask; for example, requiring every endpoint to be migrated, the old client removed, and tests to pass. Instead of repeatedly asking it to think harder, users should focus on boundaries and acceptance criteria.
In Claude Code, a project-level CLAUDE.md file can state which steps should continue and which actions require approval. The guide also recommends assigning large audits, migrations, or reviews to subagents while checking each subagent’s evidence. For lengthy runs, keeping a checklist in a file such as TASKS.md makes progress easier to recover after older conversation turns are summarized. For design work, naming specific unwanted patterns is more useful than simply asking for something “non-generic.”
Build review into the Opus 5.5 workflow
When a long task ends, users should first check what decisions or approvals Claude still needs, then read the full summary. The guide says Opus 5.5 reports completed work, findings, and open needs more clearly; users can also ask it to list only merge-blocking issues, include files and lines, and mark anything it could not confirm. In Claude apps, uploading the actual chart, screenshot, or deck is preferable to retyping data when checking spatial relationships and consistency in dates, numbers, or names.
Safety flags remain an important limitation
This workflow does not remove the need for human oversight. The guide says Opus 5.5 launches with stronger biosecurity and cybersecurity safeguards; when a message is flagged, Claude apps and Claude Code generally switch to an older model, and the trigger may come from files or search results in the conversation rather than only the latest message. Legitimate security work can still be flagged incorrectly, so users may switch back, edit the last message, or submit feedback. The guide also advises against requesting hidden reasoning, favoring verifiable conclusions, evidence, and uncertainty instead.