--- title: "Changes to Create a Message Batch" method: POST path: "/v1/messages/batches?beta=true" --- # Changes to Create a Message Batch `POST /v1/messages/batches?beta=true` > Every recorded change to this operation, newest first. ## Timeline Changed in 50 of 287 revisions. - **2026-11-09** `9b8a60482a33`: 12 breaking, 12 info - **2026-11-09** `3fc8060329f5`: 12 breaking, 12 info - **2026-11-09** `d53195e9d075`: 12 info - **2026-11-05** `037a593978dc`: 1 info - **2026-10-23** `f538a797852c`: 1 info - **2026-10-23** `8071e43a8476`: 1 info - **2026-10-22** `376dea998624`: 2 info - **2026-10-21** `94c83daca660`: 1 breaking, 7 warning, 2 info - **2026-10-21** `b6f3fef9c0b5`: 1 info - **2026-10-14** `e6a88013f0b2`: 1 info - **2026-10-09** `ee978b5e1294`: 7 breaking, 7 info - **2026-10-08** `5b6f4c063051`: 2 breaking, 10 info - **2026-10-07** `2705c258c5dc`: 7 info - **2026-09-30** `d721a6487a16`: 7 breaking, 8 info - **2026-09-30** `ab91b3e513b5`: 1 info - **2026-09-28** `3cd29369f196`: 7 breaking, 7 info - **2026-09-28** `36794f5ab00f`: 4 info - **2026-09-28** `4cb0d5a0056a`: 1 info - **2026-09-22** `257523f5aeb5`: 13 info - **2026-09-18** `3144b1e8c9e4`: 1 breaking, 1 warning - **2026-09-15** `54c20b5c11d2`: 2 info - **2026-09-15** `3449c49f2da8`: 4 info - **2026-09-10** `e46a40fc336b`: 1 info - **2026-09-04** `4789294140a2`: 17 info - **2026-09-01** `d1d189d791d1`: 2 warning, 11 info - **2026-08-26** `dca67b3e5234`: 4 info - **2026-08-19** `67ee007cda1c`: 10 info - **2026-08-19** `e9d8152420c3`: 1 breaking, 1 info - **2026-08-13** `6e9020ec2b41`: 30 info - **2026-08-07** `538e9bd0db77`: 5 breaking - **2026-07-24** `a97790bd7f18`: 4 breaking, 10 info - **2026-06-30** `7caa9a75ddbc`: 5 info - **2026-06-29** `4465f98f96c1`: 1 info - **2026-06-24** `82c21eb736c8`: 1 warning, 1 info - **2026-06-18** `063bcb9d6cf9`: 5 breaking, 24 info - **2026-06-09** `00259327305f`: 2 breaking, 6 info - **2026-06-06** `546c704d347b`: 2 breaking, 5 info - **2026-05-28** `f9d488f9290d`: 8 info - **2026-05-19** `40e330aba8bc`: 1 info - **2026-05-13** `400ce646c6b2`: 1 info - **2026-04-30** `6edc6519fd32`: 1 info - **2026-04-16** `e0696f59ae07`: 2 breaking, 6 info - **2026-04-09** `d87d3ef6f636`: 4 info - **2026-04-08** `69486316563e`: 1 breaking, 4 info - **2026-03-18** `dd2dcd00a757`: 1 info - **2026-03-16** `7fce94a3c9f7`: 1 breaking, 4 info - **2026-02-19** `29a6b7ba5194`: 1 info - **2026-02-18** `5387c517ad6a`: 20 info - **2026-02-17** `53a0f3638030`: 9 info - **2026-02-07** `fee5dc365a49`: 1 info ## Changes - **2026-11-09** `9b8a60482a33`: 12 breaking, 12 info - removed `subschema #1, subschema #2` from the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #3: SystemInputMessage]/content/anyOf[subschema #2: Blocks]/items/oneOf[subschema #2: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #3: SystemInputMessage]/content/anyOf[subschema #2: Blocks]/items/oneOf[subschema #2: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - **2026-11-09** `3fc8060329f5`: 12 breaking, 12 info - removed `subschema #1, subschema #2` from the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/messages/items/oneOf[subschema #3: SystemInputMessage]/content/anyOf[subschema #2: Blocks]/items/oneOf[subschema #2: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/model` request property `anyOf` list - removed `subschema #1, subschema #2` from the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #3: SystemInputMessage]/content/anyOf[subschema #2: Blocks]/items/oneOf[subschema #2: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - **2026-11-09** `d53195e9d075`: 12 info - added `subschema #1, subschema #2` to the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #1: UserInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #2: AssistantInputMessage]/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/messages/items/oneOf[subschema #3: SystemInputMessage]/content/anyOf[subschema #2: Blocks]/items/oneOf[subschema #2: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/model` request property `anyOf` list - added `subschema #1, subschema #2` to the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - **2026-11-05** `037a593978dc`: 1 info - added the enum value `admin-user-sign-out-2026-10-08` to the property `items/anyOf[subschema #2]/` of the `header` request parameter `anthropic-beta` - **2026-10-23** `f538a797852c`: 1 info - added the enum value `experimental-claude-tag-2026-10-21` to the property `items/anyOf[subschema #2]/` of the `header` request parameter `anthropic-beta` - **2026-10-23** `8071e43a8476`: 1 info - added the enum value `analytics-usage-cost-2026-08-24` to the property `items/anyOf[subschema #2]/` of the `header` request parameter `anthropic-beta` - **2026-10-22** `376dea998624`: 2 info - added the new optional request property `requests/items/params/thread` - added the enum value `message-threads-2026-08-12` to the property `items/anyOf[subschema #2]/` of the `header` request parameter `anthropic-beta` - **2026-10-21** `94c83daca660`: 1 breaking, 7 warning, 2 info - the `requests/items/params/messages/items/` request property type changed from `object` to no type - removed the request property `requests/items/params/messages/items/clear_at` - removed the request property `requests/items/params/messages/items/content` - removed the request property `requests/items/params/messages/items/output_config` - removed the request property `requests/items/params/messages/items/role` - removed the request property `requests/items/params/temperature` - removed the request property `requests/items/params/top_k` - removed the request property `requests/items/params/top_p` - added `assistant, system, user` discriminator mapping keys to the `requests/items/params/messages/items/` request property - added `#/components/schemas/BetaUserInputMessage, #/components/schemas/BetaAssistantInputMessage, #/components/schemas/BetaSystemInputMessage` to the `requests/items/params/messages/items/` request property `oneOf` list - **2026-10-21** `b6f3fef9c0b5`: 1 info - added the enum value `webhooks-2026-10-07` to the property `items/anyOf[subschema #2]/` of the `header` request parameter `anthropic-beta` - **2026-10-14** `e6a88013f0b2`: 1 info - added the enum value `telemetry-destinations-2026-08-11` to the property `items/anyOf[subschema #2]/` of the `header` request parameter `anthropic-beta` - **2026-10-09** `ee978b5e1294`: 7 breaking, 7 info - removed `subschema #15, subschema #16` from the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - removed `subschema #15, subschema #16` from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #15, subschema #16` from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #15, subschema #16` from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - removed `subschema #15, subschema #16` from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - removed `subschema #15, subschema #16` from the `requests/items/params/model` request property `anyOf` list - removed `subschema #15, subschema #16` from the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #15, subschema #16` to the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - added `subschema #15, subschema #16` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #15, subschema #16` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #15, subschema #16` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - added `subschema #15, subschema #16` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - added `subschema #15, subschema #16` to the `requests/items/params/model` request property `anyOf` list - added `subschema #15, subschema #16` to the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - **2026-10-08** `5b6f4c063051`: 2 breaking, 10 info - the `error` response's property type changed from no type to `object` for status `400` - the `error` response's property type changed from no type to `object` for status `429` - added the optional property `error/details` to the response with the `400` status - added the optional property `error/details` to the response with the `429` status - removed discriminator from `error` response property for the response status `400` - removed discriminator from `error` response property for the response status `429` - removed `#/components/schemas/BetaInvalidRequestError, #/components/schemas/BetaAuthenticationError, #/components/schemas/BetaBillingError, #/components/schemas/BetaPermissionError, #/components/schemas/BetaNotFoundError, #/components/schemas/BetaRateLimitError, #/components/schemas/BetaGatewayTimeoutError, #/components/schemas/BetaAPIError, #/components/schemas/BetaOverloadedError` from the `error` response property `oneOf` list for the response status `400` - removed `#/components/schemas/BetaInvalidRequestError, #/components/schemas/BetaAuthenticationError, #/components/schemas/BetaBillingError, #/components/schemas/BetaPermissionError, #/components/schemas/BetaNotFoundError, #/components/schemas/BetaRateLimitError, #/components/schemas/BetaGatewayTimeoutError, #/components/schemas/BetaAPIError, #/components/schemas/BetaOverloadedError` from the `error` response property `oneOf` list for the response status `429` - added the required property `error/message` to the response with the `400` status - added the required property `error/message` to the response with the `429` status - added the required property `error/type` to the response with the `400` status - added the required property `error/type` to the response with the `429` status - **2026-10-07** `2705c258c5dc`: 7 info - added `subschema #1` to the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - added `subschema #1` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - added `subschema #1` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - added `subschema #1` to the `requests/items/params/model` request property `anyOf` list - added `subschema #1` to the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - **2026-09-30** `d721a6487a16`: 7 breaking, 8 info - removed `subschema #18, subschema #19` from the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - removed `subschema #18, subschema #19` from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #18, subschema #19` from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #18, subschema #19` from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - removed `subschema #18, subschema #19` from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - removed `subschema #18, subschema #19` from the `requests/items/params/model` request property `anyOf` list - removed `subschema #18, subschema #19` from the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added the enum value `spend-limit-reads-2026-09-26` to the property `items/anyOf[subschema #2]/` of the `header` request parameter `anthropic-beta` - added `subschema #18, subschema #19` to the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - added `subschema #18, subschema #19` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #18, subschema #19` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #18, subschema #19` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - added `subschema #18, subschema #19` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - added `subschema #18, subschema #19` to the `requests/items/params/model` request property `anyOf` list - added `subschema #18, subschema #19` to the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - **2026-09-30** `ab91b3e513b5`: 1 info - added the enum value `ce-plugins-2026-09-01` to the property `items/anyOf[subschema #2]/` of the `header` request parameter `anthropic-beta` - **2026-09-28** `3cd29369f196`: 7 breaking, 7 info - removed `subschema #4` from the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - removed `subschema #4` from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #4` from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - removed `subschema #4` from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - removed `subschema #4` from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - removed `subschema #4` from the `requests/items/params/model` request property `anyOf` list - removed `subschema #4` from the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #5` to the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - added `subschema #1, subschema #5` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes/anyOf[subschema #1]/items/oneOf[subschema #1: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #5` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool/oneOf[subschema #4: ToolChangeToolDefinition]/definition/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `subschema #1, subschema #5` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - added `subschema #1, subschema #5` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - added `subschema #1, subschema #5` to the `requests/items/params/model` request property `anyOf` list - added `subschema #1, subschema #5` to the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - **2026-09-28** `36794f5ab00f`: 4 info - added `between_tools` discriminator mapping keys to the `requests/items/params/fallbacks/anyOf[subschema #1]/items/thinking/anyOf[subschema #1]/` request property - added `between_tools` discriminator mapping keys to the `requests/items/params/thinking` request property - added `#/components/schemas/BetaThinkingConfigBetweenTools` to the `requests/items/params/fallbacks/anyOf[subschema #1]/items/thinking/anyOf[subschema #1]/` request property `oneOf` list - added `#/components/schemas/BetaThinkingConfigBetweenTools` to the `requests/items/params/thinking` request property `oneOf` list - **2026-09-28** `4cb0d5a0056a`: 1 info - removed discriminator from `requests/items/params/context_management/anyOf[subschema #1: ContextManagementConfig]/edits/items/oneOf[subschema #2: ClearThinking20251015]/keep/anyOf[subschema #1]/` request property - **2026-09-22** `257523f5aeb5`: 13 info - added the new optional request property `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/tool_changes` - added the new optional request property `requests/items/params/tools/items/oneOf[subschema #28: MCPToolset]/tools` - added the enum value `inline-tools-2026-09-15` to the property `items/anyOf[subschema #2]/` of the `header` request parameter `anthropic-beta` - added the enum value `mcp-client-2026-09-15` to the property `items/anyOf[subschema #2]/` of the `header` request parameter `anthropic-beta` - added `subschema #3` to the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - added `subschema #3` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #23: RequestFallbackBlock -> subschema #24: RequestFallbackBlock]/from/model` request property `anyOf` list - added `subschema #3` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #23: RequestFallbackBlock -> subschema #24: RequestFallbackBlock]/to/model` request property `anyOf` list - added `subschema #3` to the `requests/items/params/model` request property `anyOf` list - added `subschema #3` to the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - added `mcp_tool_listing` discriminator mapping keys to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/` request property - added `tool_definition` discriminator mapping keys to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool` request property - added `#/components/schemas/BetaRequestMCPToolListingBlock` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/` request property `oneOf` list - added `#/components/schemas/BetaToolChangeToolDefinition` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #21: RequestToolAdditionBlock]/tool` request property `oneOf` list - **2026-09-18** `3144b1e8c9e4`: 1 breaking, 1 warning - for the `header` request parameter `anthropic-beta`, the type changed from `string` to `array` - for the `header` request parameter `anthropic-beta`, the type of property `items/` changed from `string` to no type - **2026-09-15** `54c20b5c11d2`: 2 info - added the new optional request property `requests/items/params/compaction` - added the new optional request property `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #20: RequestCompactionBlock]/signature` - **2026-09-15** `3449c49f2da8`: 4 info - added the new optional request property `requests/items/params/tools/items/oneOf[subschema #19: WebFetchTool_20250910]/url_sources` - added the new optional request property `requests/items/params/tools/items/oneOf[subschema #21: WebFetchTool_20260209]/url_sources` - added the new optional request property `requests/items/params/tools/items/oneOf[subschema #22: WebFetchTool_20260309]/url_sources` - added the new optional request property `requests/items/params/tools/items/oneOf[subschema #24: WebFetchTool_20260318]/url_sources` - **2026-09-10** `e46a40fc336b`: 1 info - added the new `content_too_large` enum value to the request property `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #11: RequestWebFetchToolResultBlock]/content/anyOf[subschema #1: RequestWebFetchToolResultError]/error_code` - **2026-09-04** `4789294140a2`: 17 info - added the new optional `header` request parameter `anthropic-workspace-id` - added the non-success response with the status `400` - added the non-success response with the status `401` - added the non-success response with the status `403` - added the non-success response with the status `404` - added the non-success response with the status `408` - added the non-success response with the status `409` - added the non-success response with the status `412` - added the non-success response with the status `413` - added the non-success response with the status `429` - added the non-success response with the status `431` - added the non-success response with the status `499` - added the non-success response with the status `500` - added the non-success response with the status `501` - added the non-success response with the status `503` - added the non-success response with the status `504` - added the non-success response with the status `529` - **2026-09-01** `d1d189d791d1`: 2 warning, 11 info - removed the request property `requests/items/params/tools/items/oneOf[subschema #14: ComputerToolset_20260801]/allowed_callers` - removed the request property `requests/items/params/tools/items/oneOf[subschema #8: BrowserToolset_20260801]/allowed_callers` - added the new optional request property `requests/items/params/fallbacks/anyOf[subschema #1]/items/thinking/anyOf[subschema #1]/oneOf[subschema #1: ThinkingConfigEnabled]/block_binding` - added the new optional request property `requests/items/params/fallbacks/anyOf[subschema #1]/items/thinking/anyOf[subschema #1]/oneOf[subschema #3: ThinkingConfigAdaptive]/block_binding` - added the new optional request property `requests/items/params/messages/items/clear_at` - added the new optional request property `requests/items/params/messages/items/output_config` - added the new optional request property `requests/items/params/thinking/oneOf[subschema #1: ThinkingConfigEnabled]/block_binding` - added the new optional request property `requests/items/params/thinking/oneOf[subschema #3: ThinkingConfigAdaptive]/block_binding` - added `subschema #2, subschema #3` to the `requests/items/params/fallbacks/anyOf[subschema #1]/items/model` request property `anyOf` list - added `subschema #2, subschema #3` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #23: RequestFallbackBlock]/from/model` request property `anyOf` list - added `subschema #2, subschema #3` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #23: RequestFallbackBlock]/to/model` request property `anyOf` list - added `subschema #2, subschema #3` to the `requests/items/params/model` request property `anyOf` list - added `subschema #2, subschema #3` to the `requests/items/params/tools/items/oneOf[subschema #25: AdvisorTool_20260301]/model` request property `anyOf` list - **2026-08-26** `dca67b3e5234`: 4 info - added the new `updates` enum value to the request property `requests/items/params/fallbacks/anyOf[subschema #1]/items/thinking/anyOf[subschema #1]/oneOf[subschema #1: ThinkingConfigEnabled]/display/anyOf[subschema #1: ThinkingDisplayMode]/` - added the new `updates` enum value to the request property `requests/items/params/fallbacks/anyOf[subschema #1]/items/thinking/anyOf[subschema #1]/oneOf[subschema #3: ThinkingConfigAdaptive]/display/anyOf[subschema #1: ThinkingDisplayMode]/` - added the new `updates` enum value to the request property `requests/items/params/thinking/oneOf[subschema #1: ThinkingConfigEnabled]/display/anyOf[subschema #1: ThinkingDisplayMode]/` - added the new `updates` enum value to the request property `requests/items/params/thinking/oneOf[subschema #3: ThinkingConfigAdaptive]/display/anyOf[subschema #1: ThinkingDisplayMode]/` - **2026-08-19** `67ee007cda1c`: 10 info - added the new optional request property `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #11: RequestWebFetchToolResultBlock]/content/anyOf[subschema #2: RequestWebFetchResultBlock]/content/source/oneOf[subschema #3: ContentBlockSource]/content/anyOf[subschema #2: beta_content_block_source_content]/items/oneOf[subschema #2: RequestImageBlock]/transformations` - added the new optional request property `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #2: RequestImageBlock]/transformations` - added the new optional request property `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #3: RequestDocumentBlock]/source/oneOf[subschema #3: ContentBlockSource]/content/anyOf[subschema #2: beta_content_block_source_content]/items/oneOf[subschema #2: RequestImageBlock]/transformations` - added the new optional request property `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #7: RequestToolUseBlock]/toolset_name` - added the new optional request property `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #8: RequestToolResultBlock]/content/anyOf[subschema #2]/items/oneOf[subschema #2: RequestImageBlock]/transformations` - added the new optional request property `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #8: RequestToolResultBlock]/content/anyOf[subschema #2]/items/oneOf[subschema #4: RequestDocumentBlock]/source/oneOf[subschema #3: ContentBlockSource]/content/anyOf[subschema #2: beta_content_block_source_content]/items/oneOf[subschema #2: RequestImageBlock]/transformations` - added the new optional request property `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #8: RequestToolResultBlock]/toolset_name` - added `browser_state` discriminator mapping keys to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #8: RequestToolResultBlock]/content/anyOf[subschema #2]/items/` request property - added `#/components/schemas/BetaBrowserToolset_20260801, #/components/schemas/BetaComputerToolset_20260801` to the `requests/items/params/tools/items/` request property `oneOf` list - added `#/components/schemas/BetaRequestBrowserStateBlock` to the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/oneOf[subschema #8: RequestToolResultBlock]/content/anyOf[subschema #2]/items/` request property `oneOf` list - **2026-08-19** `e9d8152420c3`: 1 breaking, 1 info - removed `#/components/schemas/BetaRequestMidConvSystemBlock` from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/` request property `oneOf` list - removed `mid_conv_system` discriminator mapping keys from the `requests/items/params/messages/items/content/anyOf[subschema #2]/items/` request property - …earlier changes are on the page: https://skmtc.dev/anthropics/apis/anthropic-api/changes/v1/messages/batches%3Fbeta=true/post --- [Operation](https://skmtc.dev/anthropics/apis/anthropic-api/docs/v1/messages/batches%3Fbeta=true/post.md) - [API](https://skmtc.dev/anthropics/apis/anthropic-api.md) - [Page](https://skmtc.dev/anthropics/apis/anthropic-api/changes/v1/messages/batches%3Fbeta=true/post)