# Send Message or Request Revision

## cURL

```bash
curl --request POST \
  --url https://api.heygen.com/v3/video-agents/{session_id} \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '\
{\
  "message": "<string>",\
  "avatar_id": "<string>",\
  "voice_id": "<string>",\
  "files": [\
    {\
      "type": "<string>",\
      "url": "<string>"\
    }\
  ]\
}'
```

### Response Codes
- 200
- 400
- 401
- 404
- 429

```json
{
  "data": {
    "session_id": "<string>",
    "run_id": "<string>",
    "title": "<string>"
  }
}
```

## Authorizations

### ApiKeyAuthBearerAuth

- **x-api-key**  
  Type: string  
  Location: header  
  Required: Yes  
  Description: HeyGen API key. Obtain from your HeyGen dashboard.

## Path Parameters

- **session_id**  
  Type: string  
  Required: Yes  
  Description: Session ID

## Body

- **message**  
  Type: string  
  Required: Yes  
  Description: Text message to the agent. Required string length: `1 - 10000`

- **avatar_id**  
  Type: string | null  
  Description: Override avatar for this message

- **voice_id**  
  Type: string | null  
  Description: Override voice for this message

- **files**  
  Type: (AssetUrl · object | AssetId · object | AssetBase64 · object)[] | null  
  Description: Optional file attachments (max 20 files). Maximum array length: `20`. Asset input via publicly accessible HTTPS URL.

- **AssetUrl**  
  - **AssetId**  
  - **AssetBase64**

## Response

### 200

- **data**  
  Type: SendMessageResponse · object  
  Description: Response from sending a message to a session.