You can request real-time entity extraction during an Agent Assist conversation. This feature automatically extracts data that matches any Dialogflow system entity in end-user expressions.
For example, if the end-user says "I want three tickets for Friday", "3" will
be extracted as a @sys.number 
entity, and "Friday" will be extracted as a @sys.date 
entity. Agent Assist provides this data to your system during
the conversation, so you can display it on the human agent's user interface.
You can then use this data to provide the human agent with additional tools,
such as a button to schedule an event when a date is extracted.
Enable real-time entity extraction
To enable real-time entity extraction, set the human_agent_assistant_config.message_analysis_config.enable_entity_extraction 
field to true 
when creating or updating a  ConversationProfile 
 
.
Get extracted data
When you call the analyzeContent 
or streamingAnalyzeContent 
method for the  Participant 
 
resource, the message.message_annotations.parts 
field of the response contains the extracted
data.

