Create a Message changedapi/messages/create
Nearest release: v2.1.284, published 8 hours before this site recorded the change. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.
Recorded here
Lines+175added
Lines−163removed
From line
1,073
where the diff opens
First seen
14 Aug 2026
this site's first read of the page
Recorded edits14to this page, all time
The whole hunk
from line 1073, old and new numbered
/
from line 1073
10731073
10741074 See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.
10751075
1076 - `string`
1076 - `"claude-sonnet-5-5" or "claude-fable-5-1" or "claude-opus-5-5" or 16 more`
10771077
1078 - `"claude-fable-5-1" or "claude-opus-5-5" or "claude-mythos-5-1" or 15 more`
1079
10801078 The model that will complete your prompt.
10811079
10821080 See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.
10831081
1082 - `"claude-sonnet-5-5"`
1083
1084 Efficient model for coding and agents
1085
10841086 - `"claude-fable-5-1"`
10851087
10861088 Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows
from line 1097
10951097
10961098 - `"claude-sonnet-5"`
10971099
1098 High-performance model for coding and agents
1100 Efficient model for coding and agents
10991101
11001102 - `"claude-fable-5"`
11011103
from line 1157
11551157
11561158 New class of intelligence, strongest in coding and cybersecurity
11571159
1160 - `string`
1161
11581162- `cache_control: optional CacheControlEphemeral or null`
11591163
11601164 Top-level cache control automatically applies a cache_control marker to the last cacheable block in the request.
from line 1279
12751279
12761280- `stream: optional boolean`
12771281
1278 Whether to incrementally stream the response using server-sent events.
1282 Whether to incrementally stream the response using server-sent events. When `true`, SDKs return a raw event stream.
12791283
1280 See [streaming](https://platform.claude.com/docs/en/build-with-claude/streaming) for details.
1284 In the TypeScript, Python and Ruby SDKs, the recommended way to stream is `messages.stream()`. It sets `stream` for you and accumulates the events into the final message. See [Streaming with SDKs](https://platform.claude.com/docs/en/build-with-claude/streaming#streaming-with-sdks) for an example in each language.
12811285
12821286- `system: optional string or array of TextBlockParam`
12831287
from line 1339
13351339
13361340 - `type: "disabled"`
13371341
1342 - `ThinkingConfigBetweenTools object`
1343
1344 - `type: "between_tools"`
1345
13381346 - `ThinkingConfigAdaptive object`
13391347
13401348 - `type: "adaptive"`
from line 3920
39123920
39133921 See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.
39143922
3915 - `string`
3923 - `"claude-sonnet-5-5" or "claude-fable-5-1" or "claude-opus-5-5" or 16 more`
39163924
3917 - `"claude-fable-5-1" or "claude-opus-5-5" or "claude-mythos-5-1" or 15 more`
3918
39193925 The model that will complete your prompt.
39203926
39213927 See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.
39223928
3929 - `"claude-sonnet-5-5"`
3930
3931 Efficient model for coding and agents
3932
39233933 - `"claude-fable-5-1"`
39243934
39253935 Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows
from line 3944
39343944
39353945 - `"claude-sonnet-5"`
39363946
3937 High-performance model for coding and agents
3947 Efficient model for coding and agents
39383948
39393949 - `"claude-fable-5"`
39403950
from line 4003
39934003 **Deprecated**: Will reach end-of-life on June 30, 2026. Please migrate to claude-mythos-5. Visit https://docs.anthropic.com/en/docs/resources/model-deprecations for more information.
39944004
39954005 New class of intelligence, strongest in coding and cybersecurity
4006
4007 - `string`
39964008
39974009 - `role: "assistant"`
39984010
No line in this hunk matches that.