# RunDetailsCallbackHandler

> **Class** in `langchain_sema4`

📖 [View in docs](https://reference.langchain.com/python/langchain-sema4/toolkits/RunDetailsCallbackHandler)

Callback handler to add run details to the run.

## Signature

```python
RunDetailsCallbackHandler(
    self,
    run_details: dict,
)
```

## Parameters

| Name | Type | Required | Description |
|------|------|----------|-------------|
| `run_details` | `dict` | Yes | Run details. |

## Extends

- `BaseCallbackHandler`

## Constructors

```python
__init__(
    self,
    run_details: dict,
) -> None
```

| Name | Type |
|------|------|
| `run_details` | `dict` |


## Properties

- `run_details`

## Methods

- [`on_tool_start()`](https://reference.langchain.com/python/langchain-sema4/toolkits/RunDetailsCallbackHandler/on_tool_start)

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[View source on GitHub](https://github.com/langchain-ai/langchain-sema4/blob/14caa588ea60d411598f096d0734099bedcca0dd/libs/sema4/langchain_sema4/toolkits.py#L34)