public com.google.cloud.vertexai.api.FunctionDeclaration getFunctionDeclarations(int index) {
      if (functionDeclarationsBuilder_ == null) {
        return functionDeclarations_.get(index);
      } else {
        return functionDeclarationsBuilder_.getMessage(index);
      }
    }
<pre>
Optional. Function tool type.
One or more function declarations to be passed to the model along with the
current user query. Model may decide to call a subset of these functions
by populating [FunctionCall][google.cloud.aiplatform.v1.Part.function_call]
in the response. User should provide a
[FunctionResponse][google.cloud.aiplatform.v1.Part.function_response] for
each function call in the next turn. Based on the function responses, Model
will generate the final response back to the user. Maximum 128 function
declarations can be provided.
</pre>

<code>
repeated .google.cloud.vertexai.v1.FunctionDeclaration function_declarations = 1 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/Tool.java