public com.google.cloud.vertexai.api.Tool.Builder addToolsBuilder() {
      return getToolsFieldBuilder()
          .addBuilder(com.google.cloud.vertexai.api.Tool.getDefaultInstance());
    }
<pre>
Optional. A list of `Tools` the model may use to generate the next
response.

A `Tool` is a piece of code that enables the system to interact with
external systems to perform an action, or set of actions, outside of
knowledge and scope of the model.
</pre>

<code>
repeated .google.cloud.vertexai.v1.Tool tools = 6 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/CountTokensRequest.java