fine-grained-tool-streaming changedagents-and-tools/tool-use/fine-grained-tool-streaming
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## Availability ### API support #### [Messages API](https://platform.claude.com/docs/en/build-with-claude/working-with-messages) ### Data handling
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22title: Fine-grained tool streaming
33url: https://platform.claude.com/docs/en/agents-and-tools/tool-use/fine-grained-tool-streaming
44description: Stream tool inputs without server-side JSON buffering for latency-sensitive applications.
5featureMetadata:
6 status: ga
7 zdr:
8 eligibility: eligible
9 note: Excludes [Covered Models](https://platform.claude.com/docs/en/manage-claude/api-and-data-retention#model-specific-data-retention-requirements).
10 supportedModels:
11 - claude-fable-5-1
12 - claude-mythos-5-1
13 - claude-fable-5
14 - claude-mythos-5
15 - claude-mythos-preview
16 - claude-opus-5-5
17 - claude-opus-5
18 - claude-sonnet-5-5
19 - claude-sonnet-5
20 - claude-haiku-5-5
21 - claude-haiku-4-5-20251001
22 - claude-opus-4-8
23 - claude-opus-4-7
24 - claude-opus-4-6
25 - claude-sonnet-4-6
26 - claude-opus-4-5-20251101
27 - claude-sonnet-4-5-20250929
28 supportedPlatforms:
29 Claude API: ga
30 Claude Platform on AWS: ga
31 Amazon Bedrock: ga
32 Amazon Bedrock (InvokeModel): ga
33 Claude Models on Google Cloud (Google managed): ga
34 Microsoft Foundry: ga
535---
636
7<Note>
8 To learn how zero data retention (ZDR) applies to this feature, see [API and data retention](https://platform.claude.com/docs/en/manage-claude/api-and-data-retention).
9</Note>
10
1137Fine-grained tool streaming delivers a tool’s input to your client as Claude generates it, without server-side buffering or JSON validation. Skipping the buffering step reduces the time to the first fragment of a large parameter, such as a document or a block of code, and the fragments arrive through the same [Streaming messages](https://platform.claude.com/docs/en/build-with-claude/streaming) events as standard tool use.
1238
1339<Warning>
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938964 Directory of Anthropic-provided tools and reference for optional tool definition properties.
939965 </Card>
940966</CardGroup>
967
968## Availability
969
970Fine-grained tool streaming is available on every model and eligible for zero data retention and HIPAA readiness.
971
972### API support
973
974#### [Messages API](https://platform.claude.com/docs/en/build-with-claude/working-with-messages)
975
976* Availability: Available
977
978| Status | Cloud platforms |
979| --------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
980| Available | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Amazon Bedrock (InvokeModel)](https://platform.claude.com/docs/en/build-with-claude/claude-on-amazon-bedrock-legacy), [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) |
981
982### Data handling
983
984[Data handling overview](https://platform.claude.com/docs/en/manage-claude/api-and-data-retention#feature-eligibility)
985
986| Item | Zero data retention | HIPAA |
987| ------ | --------------------------------------------------------------------------------------------------------------------------------------------------------- | -------- |
988| Status | Eligible (excludes [Covered Models](https://platform.claude.com/docs/en/manage-claude/api-and-data-retention#model-specific-data-retention-requirements)) | Eligible |
989
990Applicable endpoints:
991
992* `/v1/messages`
941993
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