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prompting-claude-sonnet-5-5 changedbuild-with-claude/prompt-engineering/prompting-claude-sonnet-5-5

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111111Next, remove older instructions such as "hold all findings for the final response." If you then want updates at predictable points, for example a line on what the model is about to do before its first tool call and a short recap at the end, say so in the system prompt. The model follows instructions like this. Updates at set points help most in human-in-the-loop work.
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113If long tool-calling turns still go quiet for longer than you want, your harness can prompt an update. Have it count consecutive tool-calling steps that send the user no text or progress update. After several in a row, for example five, append a one-turn reminder after the latest tool results. Send it as a [turn-scoped system message](https://platform.claude.com/docs/en/build-with-claude/mid-conversation-system-messages#turn-scoped-system-messages) (beta), with text like this:
113If long tool-calling turns still go quiet for longer than you want, your harness can prompt an update. Have it count consecutive tool-calling steps that send the user no text or progress update. After several in a row, for example five, append a one-turn reminder after the latest tool results. Send it as a [turn-scoped system message](https://platform.claude.com/docs/en/build-with-claude/mid-conversation-system-messages#turn-scoped-system-messages) (beta), with text such as the following:
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115115```text wrap
116116The user hasn't heard from you in a while — say in a few words what you're doing, then continue.
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135135Claude Sonnet 5.5 is trained to resist indirect prompt injection, meaning malicious instructions that arrive through tool results and other content it reads during a task. Sometimes it treats a genuine user message as a possible injection. Suppose a message the user typed mid-task reaches the model as a [mid-conversation system message](https://platform.claude.com/docs/en/build-with-claude/mid-conversation-system-messages) placed directly after a tool result, or inside a `tool_result` block. The model can then tell the user that the tool result contained text posing as a message from them, and ignore the message or ask the user to confirm it.
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137A token countdown that your harness adds after every tool result can cause this. So can letting users send messages while the model is partway through a multistep turn, or having your harness add instructions or context after the tool results on every step. In each case, text arrives right after the tool results. With a countdown or per-step instructions, that can occur on every tool call. An occasional one-turn reminder, like the one in [User-facing progress updates](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-sonnet-5-5#user-facing-progress-updates), arrives far less often. If you see this reaction to a reminder of your own, send the reminder less often. To avoid the misread:
137A token countdown that your harness adds after every tool result can cause this. So can letting users send messages while the model is partway through a multistep turn, or having your harness add instructions or context after the tool results on every step. In each case, text arrives right after the tool results. With a countdown or per-step instructions, that can occur on every tool call. An occasional one-turn reminder, such as the one in [User-facing progress updates](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-sonnet-5-5#user-facing-progress-updates), arrives far less often. If you see this reaction to a reminder of your own, send the reminder less often. To avoid the misread:
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139139* Never put user text inside a `tool_result` block. The model misreads that placement most often.
140140* Deliver mid-turn user input as a user turn. Append the user's words as a text block in the user message that carries the `tool_result` blocks, after the last `tool_result`.
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