public Builder addTools(int index, com.google.cloud.vertexai.api.Tool.Builder builderForValue) {
      if (toolsBuilder_ == null) {
        ensureToolsIsMutable();
        tools_.add(index, builderForValue.build());
        onChanged();
      } else {
        toolsBuilder_.addMessage(index, builderForValue.build());
      }
      return this;
    }
<pre>
Optional. Input only. Immutable. A list of `Tools` the model may use to
generate the next response
</pre>

<code>
repeated .google.cloud.vertexai.v1.Tool tools = 5 [(.google.api.field_behavior) = OPTIONAL, (.google.api.field_behavior) = IMMUTABLE, (.google.api.field_behavior) = INPUT_ONLY];
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/CachedContent.java