Parallel tool call and client error

Hi,
Using the Mistral AI Provider by @saarnilauri and providing the prompt builder with a set of abilities, the Mistral model can return multiple tool call requests in a single answer (if not disabled with a model custom config key).

Detecting the function call request using WP_AI_Client_Ability_Function_Resolver, I execute the requested abilities with the class method execute_abilities getting back a Message. Everything fine.

When I try to send that message to the model, the operation is blocked by the AI Client with the error "The API only allows a single function response, as the only content of the message" from the AbstractOpenAiCompatibleTextGenerationModel::getMessagePartContentData().

Looking at the whole process, the method prepareMessagesParam() of the same class seems to process only a single function response within a message.

I don't know if it's something that should be extended or if it's a required behavior.

Thank you, Stefano.
PS: with WP 7.1

Start by tracing prepareMessagesParam() and AbstractOpenAiCompatibleTextGenerationModel::getMessagePartContentData() with a Message containing multiple function responses. Reproduce the Mistral parallel tool-call flow described in the issue and inspect how execute_abilities() constructs that Message. Done means the expected handling of multiple function responses is established and the client no longer rejects a valid message, or the required single-response behavior is clearly documented.