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migration-guide changedmodels/opus-5-5/migration-guide

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Lines+10added
Lines−7removed
From line 115 where the diff opens
First seen 23 Sep 2026 this site's first read of the page
Recorded edits20to this page, all time

The whole hunk

from line 115, old and new numbered
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from line 115
115115 Model = Model.ClaudeOpus5_5,
116116 MaxTokens = 4096,
117117 Messages = [
118 new UserMessageParam {
118 new UserMessageParam
119 {
119120 Content = "Analyze the trade-offs between microservices and monolithic architectures"
120121 }
121122 ],
from line 837
836837 // strict tool use: every call matches the tool's input_schema
837838 .tools(tools.stream()
838839 .map(tool -> tool.tool()
839 .map(customTool -> customTool.toBuilder().strict(true).build())
840 .map(customTool -> customTool.toBuilder()
841 .strict(true)
842 .build())
840843 .map(ToolUnion::ofTool)
841844 .orElse(tool))
842845 .toList())
from line 1472
14691472 $message = $client->messages->create(
14701473 maxTokens: 16000,
14711474 messages: [['role' => 'user', 'content' => '...']],
1472 model: 'claude-opus-5-5',
1475 model: Model::CLAUDE_OPUS_5_5,
14731476 thinking: ['type' => 'adaptive'],
14741477 outputConfig: ['effort' => 'high'], // or 'max', 'xhigh', 'medium', 'low'
14751478 );
from line 1523
15201523 
15211524 High-resolution support is automatic and requires no beta header or client-side opt-in. Two things to plan for:
15221525 
1523 * Full-resolution images can use up to approximately 3x more image tokens than on prior models (up to 4,784 tokens per image, compared to the previous cap of roughly 1,600 tokens per image). Re-budget `max_tokens` and cost expectations for image-heavy workloads, or downsample before sending if you do not need the additional fidelity.
1526 * Full-resolution images can use up to approximately 3x more image tokens than on prior models (up to 4,784 tokens for each image, compared to the previous cap of roughly 1,600 tokens). Re-budget `max_tokens` and cost expectations for image-heavy workloads, or downsample before sending if you do not need the additional fidelity.
15241527 * Pointing and bounding-box coordinates returned by the model are 1:1 with actual image pixels on Claude Opus 4.7, so no scale-factor conversion is required.
15251528 
15261529 See [High-resolution image support on Claude Opus 4.7](https://platform.claude.com/docs/en/build-with-claude/vision#high-resolution-image-support-on-claude-opus-4-7) for details.
from line 1538
15351538 
153615391. **Prefill removal** is covered in the [breaking changes for migrating from Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-5-5/migration-guide#opus-46-breaking-changes).
15371540 
15382. **Tool parameter quoting:** Claude Opus 4.6 and later models might produce slightly different JSON string escaping in tool call arguments (for example, different handling of Unicode escapes or forward slash escaping). If you parse tool call `input` as a raw string rather than using a JSON parser, verify your parsing logic. Standard JSON parsers (such as `json.loads()` or `JSON.parse()`) handle these differences automatically.
15412. **Tool parameter quoting:** Claude Opus 4.6 and later models might produce slightly different JSON string escaping in tool call arguments (for example, different handling of Unicode escapes or forward slash escaping). If you parse tool call `input` as a raw string rather than using a JSON parser, check your parsing logic. Standard JSON parsers (such as `json.loads()` or `JSON.parse()`) handle these differences automatically.
15391542 
15401543#### Recommended changes
15411544 
from line 1635
16321635 ```
16331636 </CodeGroup>
16341637 
1635 * **Text editor:** Use `text_editor_20250728` and `str_replace_based_edit_tool`. See [Text editor tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/text-editor-tool) documentation for details.
1636 * **Code execution:** Upgrade to `code_execution_20260521`. See [Code execution tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/code-execution-tool#upgrade-to-latest-tool-version) documentation for migration instructions.
1638 * **Text editor:** Use `text_editor_20250728` and `str_replace_based_edit_tool`. See the [Text editor tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/text-editor-tool) documentation for details.
1639 * **Code execution:** Upgrade to `code_execution_20260521`. See the [Code execution tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/code-execution-tool#upgrade-to-latest-tool-version) documentation for migration instructions.
16371640 * **Computer use:** On the Claude API and Claude Models on Google Cloud (Google managed), Claude Opus 5.5 accepts computer use only as the `computer_toolset_20260801` toolset: the earlier `computer_20250124` and `computer_20251124` tools are rejected there. See the [computer use breaking change](https://platform.claude.com/docs/en/models/opus-5-5/migration-guide#computer-use-toolset).
16381641 
163916423. **Handle the `refusal` stop reason**
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