---
url: >-
  https://adk.nht.io/api/@nhtio/adk/batteries/llm/openai_responses/types/interfaces/OpenAIResponsesFunctionCallArgumentsDeltaEvent.md
description: SSE event emitted when a fragment of a tool call's JSON arguments streams in.
---

# Interface: OpenAIResponsesFunctionCallArgumentsDeltaEvent

Defined in: [src/batteries/llm/openai\_responses/types.ts:446](https://github.com/NHTIO/ADK/blob/v1.20261003.0/src/src/batteries/llm/openai_responses/types.ts#L446)

SSE event emitted when a fragment of a tool call's JSON arguments streams in.

## Extends

* `OpenAIResponsesStreamEventBase`

## Properties

| Property                                                 | Type                                       | Description                                                                  | Overrides                             | Inherited from                                   | Defined in                                                                                                                                              |
| -------------------------------------------------------- | ------------------------------------------ | ---------------------------------------------------------------------------- | ------------------------------------- | ------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------- |
|  `delta`                      | `string`                                   | The incremental arguments-string fragment to append.                         | -                                     | -                                                | [src/batteries/llm/openai\_responses/types.ts:454](https://github.com/NHTIO/ADK/blob/v1.20261003.0/src/src/batteries/llm/openai_responses/types.ts#L454) |
|  `item_id`                  | `string`                                   | The id of the function-call item this delta belongs to.                      | -                                     | -                                                | [src/batteries/llm/openai\_responses/types.ts:450](https://github.com/NHTIO/ADK/blob/v1.20261003.0/src/src/batteries/llm/openai_responses/types.ts#L450) |
|  `output_index`        | `number`                                   | The index of the function-call item within `response.output`.                | -                                     | -                                                | [src/batteries/llm/openai\_responses/types.ts:452](https://github.com/NHTIO/ADK/blob/v1.20261003.0/src/src/batteries/llm/openai_responses/types.ts#L452) |
|  `sequence_number?` | `number`                                   | Monotonically increasing sequence number for this event within the stream.   | -                                     | `OpenAIResponsesStreamEventBase.sequence_number` | [src/batteries/llm/openai\_responses/types.ts:310](https://github.com/NHTIO/ADK/blob/v1.20261003.0/src/src/batteries/llm/openai_responses/types.ts#L310) |
|  `type`                        | `"response.function_call_arguments.delta"` | Event-type discriminator; always `'response.function_call_arguments.delta'`. | `OpenAIResponsesStreamEventBase.type` | -                                                | [src/batteries/llm/openai\_responses/types.ts:448](https://github.com/NHTIO/ADK/blob/v1.20261003.0/src/src/batteries/llm/openai_responses/types.ts#L448) |