Messages changedapi/messages
Nearest release: v2.1.301, published 11 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.
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Lines−1removed
From line
1,275
where the diff opens
First seen
14 Aug 2026
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Recorded edits24to this page, all time
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from line 1275, old and new numbered
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from line 1275
12751275
12761276 - `"standard_only"`
12771277
1278- `speed: optional "standard" or "fast" or null`
1279
1280 The inference speed mode for this request. `"fast"` enables high output-tokens-per-second inference.
1281
1282 Some models require the `fast-mode-2026-02-01` beta header for any `speed` value. See [fast mode](https://platform.claude.com/docs/en/build-with-claude/fast-mode?sdk_languages=http) for which models.
1283
1284 - `"standard"`
1285
1286 - `"fast"`
1287
12781288- `stop_sequences: optional array of string`
12791289
12801290 Custom text sequences that will cause the model to stop generating.
from line 4210
42004210
42014211 - `"batch"`
42024212
4213 - `speed: "standard" or "fast" or null`
4214
4215 The inference speed mode used for this request.
4216
4217 - `"standard"`
4218
4219 - `"fast"`
4220
42034221- `RawMessageStreamEvent = RawMessageStartEvent or RawMessageDeltaEvent or RawMessageStopEvent or 3 more`
42044222
42054223 - `RawMessageStartEvent object`
from line 4527
45094527 "web_fetch_requests": 2,
45104528 "web_search_requests": 0
45114529 },
4512 "service_tier": "standard"
4530 "service_tier": "standard",
4531 "speed": "standard"
45134532 }
45144533}
45154534```
from line 5715
56965715
56975716 The JSON schema of the format
56985717
5718- `speed: optional "standard" or "fast" or null`
5719
5720 The inference speed mode for this request. `"fast"` enables high output-tokens-per-second inference.
5721
5722 Some models require the `fast-mode-2026-02-01` beta header for any `speed` value. See [fast mode](https://platform.claude.com/docs/en/build-with-claude/fast-mode?sdk_languages=http) for which models.
5723
5724 - `"standard"`
5725
5726 - `"fast"`
5727
56995728- `system: optional string or array of TextBlockParam`
57005729
57015730 System prompt.
from line 8559
85308559
85318560 default: tool_use
85328561
8533 - `id: string`
8534
8535 pattern: ^[a-zA-Z0-9_-]+$
8536
8537 - `caller: ToolUseCaller`
8538
8539 Which party invoked the tool call: the model directly, or a server tool on its behalf.
8540
8541 - `DirectCaller object`
8542
8543 Tool invocation directly from the model.
8544
8545 - `type: "direct"`
8546
8547 - `ServerToolCaller object`
8548
8549 Tool invocation generated by a server-side tool.
8550
8551 - `type: "code_execution_20250825"`
8552
8553 - `tool_id: string`
8554
8555 pattern: ^srvtoolu_[a-zA-Z0-9_]+$
8556
8557 - `ServerToolCaller20260120 object`
8558
8559 - `type: "code_execution_20260120"`
8560
8561 - `tool_id: string`
8562
8563 pattern: ^srvtoolu_[a-zA-Z0-9_]+$
8564
8565 - `input: BrowserHoldKeyInput`
8566
8567 Hold a key or key chord down for a duration, then release it. Uses the same key
8568 names and "+" chord syntax as the key action.
8569
8570 - `duration: number`
8571
8572 Seconds to hold the key down (maximum 30).
8573
8574 minimum: 0, maximum: 30
8575
8576 - `text: string`
8577
8578 The key or chord
8562 - `i
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