# What changed in @ai-sdk/anthropic

> 78 changes in @ai-sdk/anthropic 2 to 4 from its official release notes, upgrade guides and advisories: 5 breaking, 34 new APIs and options. Each one cited. Sources checked 2026-10-18. HTML: https://unstale.sh/npm/@ai-sdk/anthropic/

To see which of these apply to a repository, run `npx @unstale/cli init` in it.

## @ai-sdk/anthropic 4

### Breaking changes

- Renames evaluate to decide. (4.0.72) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.72)
- For Claude Sonnet 5.5, disabled thinking is replaced with `between_tools`, `reasoning: 'none'` maps to `between_tools`, and budget-based thinking is converted to adaptive thinking. (4.0.67) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.67)
- For models that always use adaptive thinking, unsupported disabled or budget-based thinking settings are dropped, `reasoning: 'none'` maps to `effort: 'low'`, and a warning is emitted. (4.0.60) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.60)
- Unsupported batch request types are now rejected. (4.0.53) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.53)

### New APIs and options

- Forwards providerOptions.vertex.labels as a header. (4.0.80) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.80)
- A typed AnthropicCitation export is available for citation data. (4.0.79) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.79)
- A typed AnthropicTextProviderMetadata export is available for text provider metadata. (4.0.79) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.79)
- Adds Claude Haiku 5.5 as a known model with a 128k max output token limit, adaptive thinking, and all five effort levels. Thinking can be disabled up to high effort; xhigh and max are lowered to high with a warning… (3.0.128, 4.0.75) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.75), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.128)
- Adds the portable max reasoning level, widening LanguageModelV4CallOptions['reasoning'] and requiring exhaustive consumers to handle max. (4.0.73) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.73)
- Exposes message-start usage through custom stream parts. (4.0.72) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.72)
- Adds Claude Sonnet 5.5 as a supported model ID in @ai-sdk/anthropic. (2.0.107, 3.0.125, 4.0.67) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.67), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.125), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.107)
- Adds the `between_tools` thinking type, the lowest thinking setting on Claude Sonnet 5.5. (2.0.107, 3.0.125, 4.0.67) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.67), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.125), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.107)
- Supports on-demand compaction and preserves signed compaction blocks. (4.0.63) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.63)
- Adds Claude Opus 5.5 as a supported model. (2.0.103, 3.0.120, 4.0.60) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.60), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.120), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.103)
- Adds the computer use toolset required for computer use on Claude Opus 5.5. (2.0.103, 3.0.120, 4.0.60) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.60), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.120), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.103)
- Adds the safeguards provider option for the dangerous tool use classifier. (3.0.127, 4.0.59) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.127), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.59)
- Adds experimental Choice, Score, and Boolean evaluations through Messages structured output, with exact labels, validated score bounds, and prompted Boolean P(true) estimates validated to be in [0, 1]. (4.0.56) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.56)
- Adds 20260318 web search and web fetch tools with response inclusion controls. (4.0.55) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.55)
- Image generation requests are now supported in batches. (4.0.53) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.53)
- Adds batch cancellation support. (4.0.52) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.52)
- Adds batch listing support. (4.0.52) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.52)
- Batch requests can now use per-request models, allowing developers to select a model for each request in a batch. (4.0.50) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.50)
- Adds support for Fable 5.1 in the Anthropic provider. (2.0.101, 3.0.116, 4.0.48) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.48), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.116), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.101)
- Upload results now expose byteSize. (4.0.47) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.47)
- Upload results now expose createdAt. (4.0.47) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.47)
- FilesV4 now optionally supports deleting files. (4.0.47) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.47)
- provider-utils adds deleteFromApi. (4.0.47) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.47)
- FilesV4 now optionally supports streaming file downloads. (4.0.47) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.47)
- Upload results now expose expiresAt. (4.0.47) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.47)
- FilesV4 call options now accept abortSignal. (4.0.47) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.47)
- FilesV4 call options now accept headers. (4.0.47) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.47)
- FilesV4 now optionally supports retrieving file metadata. (4.0.47) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.47)
- provider-utils adds streaming multipart uploads with deterministic part ordering and failure-path stream teardown. (4.0.47) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.47)
- Upload data now supports the `{ type: 'stream' }` variant. (4.0.47) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.47)
- Accepts webhookUrl for batch completions; the gateway provider registers it, while direct Anthropic and OpenAI batch providers return an unsupported warning when it is provided. (4.0.42) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.42)
- The gateway provider exports typed async-job metadata for batch completions. (4.0.42) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.42)

### Behavior and default changes

- For Claude Haiku 5.5, an enabled thinking configuration with budgetTokens is converted to adaptive thinking with a warning because the model does not support thinking token budgets. (2.0.109, 3.0.128, 4.0.75) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.75), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.128), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.109)
- For Claude Sonnet 5.5, `structuredOutputMode: 'jsonTool'` falls back to native structured outputs with a warning. (2.0.107, 3.0.125, 4.0.67) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.67), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.125), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.107)
- For Claude Sonnet 5.5, `required` and named tool choices fall back to `auto` with a warning because forced tool use is rejected. (2.0.107, 3.0.125, 4.0.67) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.67), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.125), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.107)
- For models that reject forced tool use, requesting `jsonTool` falls back to native structured outputs with a warning. (2.0.103, 3.0.120, 4.0.60) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.60), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.120), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.103)
- For models that reject forced tool use, `required` and named tool choices fall back to `auto` with a warning. (3.0.120, 4.0.60) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.60), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.120)
- Preserved thinking support now covers prefix_mismatch_behavior: 'error'. (3.0.118, 4.0.53) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.53), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.118)
- Batch requests support the full language-model option surface. (4.0.46) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.46)

### Fixes and other changes

- Support provider-referenced files in tool results. (4.0.81) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.81)
- When manual thinking is enabled with a required or named tool choice, falls back to automatic tool choice with a warning to avoid an Anthropic API 400 error. (3.0.131, 4.0.80) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.80), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.131)
- Named tool choices send only the selected tool. (3.0.131, 4.0.80) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.80), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.131)
- Retrieved web-search sources are kept separate from normalized inline citations on text parts and text-end events. (4.0.79) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.79)
- Tools are preserved when tool calls are disabled. (3.0.129, 4.0.79) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.79), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.129)
- Failed tool search results are preserved in conversation history. (3.0.129, 4.0.79) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.79), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.129)
- Generation, streaming, and batch results preserve every supported web and document citation kind, with document source compatibility and web citation source fallbacks when retrieval results are unavailable. (4.0.79) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.79)
- Avoids unsupported strict mode warnings when tools set strict to false. (4.0.77) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.77)
- Uses the JSON tool fallback for structured output on Amazon Bedrock. (4.0.75) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.75)
- JSONL rows are limited to 64 MB during batch result downloads. (4.0.73) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.73)
- Adds the required beta when replaying server-side fallback blocks. (4.0.72) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.72)
- Preserves invalid toolset calls. (4.0.71) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.71)
- Preserves server-side fallback boundaries when replaying assistant messages. (4.0.69) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.69)
- The User-Agent header is now standards-compliant. (4.0.68) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.68)
- After pruning, missing source code execution caller metadata is omitted before a subsequent user message and a warning is emitted; active tool continuations retain caller metadata. (4.0.67) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.67)
- With `between_tools` thinking on Claude Sonnet 5.5, `xhigh` and `max` effort are lowered to `high` with a warning because the API rejects them. (2.0.107, 3.0.125, 4.0.67) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.67), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.125), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.107)
- Empty compaction blocks are omitted from replay. (4.0.61) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.61)
- Uses the documented beta header for per-message effort. (2.0.103, 3.0.120, 4.0.60) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.60), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.120), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.103)
- Recognizes dated Google Vertex Claude 4 model IDs when selecting model capabilities. (4.0.49) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.49)
- The core uploadFile() helper now forwards abortSignal. (4.0.47) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.47)
- The core uploadFile() helper now forwards headers. (4.0.47) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.47)
- Provider metadata now preserves native message batch request counts. (4.0.46) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%404.0.46)

## @ai-sdk/anthropic 3

### Breaking changes

- On Claude Sonnet 5.5, disabled thinking is replaced with `between_tools` thinking and budget-based thinking is converted to adaptive thinking. (3.0.125) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.125)

### New APIs and options

- Adds the Claude Haiku 5.5 model ID to @ai-sdk/anthropic. (3.0.128) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.128)

### Behavior and default changes

- For models that always use adaptive thinking, the provider drops unsupported disabled or budget-based thinking settings and emits a warning. (2.0.103, 3.0.120) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.120), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.103)

### Fixes and other changes

- After pruning conversation history, dangling caller metadata whose source code execution call is missing is omitted before a subsequent user message, with a warning; retained tool calls and results are preserved, and active tool continuations are unchanged. (3.0.125) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.125)
- Effort updates are preserved on empty system messages at the beginning of a conversation, including consecutive updates. (2.0.106, 3.0.123) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%403.0.123), [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.106)

## @ai-sdk/anthropic 2

### New APIs and options

- Adds Claude Haiku 5.5 as a supported model, recognized with a 128k maximum output token limit and all five effort levels. (2.0.109) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.109)

### Behavior and default changes

- When thinking is disabled, it is supported up to `high` effort; `xhigh` and `max` are lowered to `high` with a warning. (2.0.109) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.109)
- For claude-sonnet-5-5, budget-based thinking is converted to adaptive thinking. (2.0.107) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.107)
- For claude-sonnet-5-5, disabled thinking is replaced with between_tools thinking, with a warning. (2.0.107) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.107)
- For models that reject forced tool use, required and named tool choices fall back to auto, with a warning. (2.0.103) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.103)

### Fixes and other changes

- Avoids forcing structured-output tools for incompatible Claude models on Amazon Bedrock. (2.0.104) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.104)
- Tool calls are preserved when using JSON structured output. (2.0.100) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.100)
- Client tool calls are ordered after provider-executed tool results. (2.0.99) — [release notes](https://github.com/vercel/ai/releases/tag/%40ai-sdk/anthropic%402.0.99)