prompting-claude-opus-5 changedbuild-with-claude/prompt-engineering/prompting-claude-opus-5
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1313Compared with Claude Opus 4.8, the improvements most relevant to prompting are:
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15* **Agentic coding:** Claude Opus 5 is strongest on difficult coding tasks: multi-file features, larger refactors, and end-to-end feature work. It completes full tasks rather than leaving stubs or placeholders, and it performs best when given the complete task specification up front and left to run. It also performs well on easier tasks like single-turn edits, where the difference from prior models is smaller.
16* **Code review and bug-finding:** Claude Opus 5 reviews code with high precision and recall: it finds real bugs at a high rate per pass, and its additional findings are mostly real issues rather than false positives. Accuracy holds at lower effort settings, which supports a fast pass at review time and a more thorough pass later. If your review prompt says "only report high-severity issues" or "be conservative," the model may follow that instruction literally and report less; ask it to report everything and filter in a separate pass instead.
15* **Agentic coding:** Claude Opus 5 is strongest on difficult coding tasks: multifile features, larger refactors, and end-to-end feature work. It completes full tasks rather than leaving stubs or placeholders, and it performs best when given the complete task specification up front and left to run. It also performs well on easier tasks such as single-turn edits, where the difference from prior models is smaller.
16* **Code review and bug-finding:** Claude Opus 5 reviews code with high precision and recall: it finds real bugs at a high rate per pass, and its additional findings are mostly real issues rather than false positives. Accuracy holds at lower effort settings, which supports a fast pass at review time and a more thorough pass later. If your review prompt says "only report high-severity issues" or "be conservative," the model might follow that instruction literally and report less; ask it to report everything and filter in a separate pass instead.
1717* **Efficiency at lower effort:** `low` and `medium` [effort](https://platform.claude.com/docs/en/build-with-claude/effort) produce strong quality at a fraction of the tokens and latency of higher settings. Start with the default (`high`) and adjust based on your evals: use `low` and `medium` liberally as your primary control for token cost and response time wherever quality holds, and step up to `xhigh` for demanding coding and agentic work. If you carried effort defaults over from a prior model, re-run an effort sweep on your own evals. See [Effort](https://platform.claude.com/docs/en/build-with-claude/effort#recommended-effort-levels-for-claude-opus-5) for the full recommendations.
18* **Vision:** Claude Opus 5 is strong on chart, document, and diagram understanding, and on UI and frontend visual replication. Re-validate any prompt-side vision workarounds you tuned for prior models; they may no longer be needed. Vision performance is strongest when the model has tools to iteratively analyze, crop, and visually verify its work, and tool use is a more cost-effective lever than thinking alone.
18* **Vision:** Claude Opus 5 is strong on chart, document, and diagram understanding, and on UI and frontend visual replication. Re-validate any prompt-side vision workarounds you tuned for prior models; they might no longer be needed. Vision performance is strongest when the model has tools to iteratively analyze, crop, and visually verify its work, and tool use is a more cost-effective lever than thinking alone.
1919* **Long-context work:** Claude Opus 5 has a [1M token context window](https://platform.claude.com/docs/en/build-with-claude/context-windows) as both the default and the maximum, and its instruction following, tool calling, and reasoning stay consistent throughout the window.
20* **Office and document tasks:** Claude Opus 5 generates and works with complex, multi-sheet spreadsheets with non-trivial formulas, and it produces well-structured slide decks. Prompt it with any specific styles or templates it needs to follow.
21* **Multi-agent coordination:** Claude Opus 5 coordinates teams of subagents well, with effective writer-verifier patterns and few cases of agents overwriting each other's work. For cost-sensitive workloads, cap delegation; see [Controlling subagent spawning](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-opus-5#controlling-subagent-spawning).
20* **Office and document tasks:** Claude Opus 5 generates and works with complex, multisheet spreadsheets with non-trivial formulas, and it produces well-structured slide decks. Prompt it with any specific styles or templates it needs to follow.
21* **Multiagent coordination:** Claude Opus 5 coordinates teams of subagents well, with effective writer-verifier patterns and few cases of agents overwriting each other's work. For cost-sensitive workloads, cap delegation; see [Controlling subagent spawning](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-opus-5#controlling-subagent-spawning).
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2323## Response length and verbosity
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6868
6969## Controlling subagent spawning
7070
71Claude Opus 5 delegates to subagents more readily than prior models. Delegation pays off on genuinely independent, sizeable tracks of work, but it multiplies cost and time when applied to small tasks. If your harness supports subagents, give explicit guidance on which scenarios warrant delegation, or set deterministic caps on how many agents can be launched. For example:
71Claude Opus 5 delegates to subagents more readily than prior models. Delegation is worthwhile for genuinely independent, sizeable tracks of work, but it multiplies cost and time when applied to small tasks. If your harness supports subagents, give explicit guidance on which scenarios warrant delegation, or set deterministic caps on how many agents can be launched. For example:
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7373```text wrap
7474Delegate to a subagent only for large tasks that are genuinely independent and parallelizable, such as a wide multi-file investigation. Do not delegate work you can finish yourself in a handful of tool calls, and do not use subagents to verify or double-check your own work. If one subagent can complete the task, use one rather than several, and keep spawn counts low.
7575```
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77If your harness is Claude Code or the Claude Agent SDK, the deterministic caps are the `CLAUDE_CODE_MAX_SUBAGENT_SPAWN_DEPTH` and `CLAUDE_CODE_MAX_CONCURRENT_SUBAGENTS` environment variables and the SDK's `max_budget_usd` (typescript: `maxBudgetUsd`) option. They require Claude Code 2.1.217 or later, so update a pinned SDK before pointing it at Claude Opus 5. Claude Code adds a delegation instruction of its own on Claude Opus 5 only when you use its `claude_code` system prompt preset; with a custom or omitted system prompt, add a delegation instruction such as the example in this section yourself. See [Cap subagent depth, concurrency, and spend](https://code.claude.com/docs/en/agent-sdk/subagents#cap-subagent-depth-concurrency-and-spend) in the Agent SDK docs.
77If your harness is Claude Code or the Claude Agent SDK, the deterministic caps are the `CLAUDE_CODE_MAX_SUBAGENT_SPAWN_DEPTH` and `CLAUDE_CODE_MAX_CONCURRENT_SUBAGENTS` environment variables and the SDK's `max_budget_usd` (typescript: `maxBudgetUsd`) option. Older versions of Claude Code don't have them, so use the latest version and update a pinned SDK before pointing it at Claude Opus 5. Claude Code adds a delegation instruction of its own on Claude Opus 5 only when you use its `claude_code` system prompt preset; with a custom or omitted system prompt, add a delegation instruction such as the example in this section yourself. See [Cap subagent depth, concurrency, and spend](https://code.claude.com/docs/en/agent-sdk/subagents#cap-subagent-depth-concurrency-and-spend) in the Agent SDK docs.
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7979## Self-correction
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105105## Reasoning in the response
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107Prompts, skills, and tool descriptions that ask Claude Opus 5 to write out its thinking or reasoning, verbatim or in a fixed format, may be declined with the `reasoning_extraction` [refusal category](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#refusal-response). Ask for a short explanation of the answer or a summary of the actions taken instead, and, if you need the reasoning, keep thinking on and read the [summarized thinking](https://platform.claude.com/docs/en/build-with-claude/thinking#summarized-thinking) blocks (`display: "summarized"`). See [Keep reasoning in thinking blocks](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#keep-reasoning-in-thinking-blocks).
107Prompts, skills, and tool descriptions that ask Claude Opus 5 to write its thinking or reasoning, verbatim or in a fixed format, might be declined with the `reasoning_extraction` [refusal category](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#refusal-response). Ask for a short explanation of the answer or a summary of the actions taken instead, and, if you need the reasoning, keep thinking on and read the [summarized thinking](https://platform.claude.com/docs/en/build-with-claude/thinking#summarized-thinking) blocks (`display: "summarized"`). See [Keep reasoning in thinking blocks](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#keep-reasoning-in-thinking-blocks).
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