Dynamics 365 Business Central: new model choice in Agent definition.

Some weeks ago I wrote on LinkedIn a short post explaining that Microsoft was slowly moving the default AI models associated to Dynamics 365 Business Central Agents (and Managed AI service) to GPT-5.3-chat and that this move was planned in a period from May to June 2026.

With the 28.1 version, there’s something more to say on this topic.

GTP-5.3-chat is now the default AI model used by Microsoft on Agents and Managed AI service. At the time of writing this post, only UK, India and Australia localizations are excluded from this change and they will come later.

This change adds also a new model switcher from the Agents page in Business Central:

The new switcher permits you to choose the model that the agent will uses to complete tasks. Default value is set to Auto (this means that the agent uses the default model that can change over time).

The currently available AI models for selection are the following:

with GPT-5.3-chat-latest setted as the default model in use.

As part of this change, new methods for controlling AI model selection programmatically from AL (useful when defining agents via code) are available in the Agent codeunit:

• procedure SetModelId(AgentUserSecurityID: Guid; ModelId: Code[30]): sets the model ID of the agent.
• procedure SetModelIdToAuto(AgentUserSecurityID: Guid): sets the agent model to auto mode, meaning the agent will use the default agent model.
• procedure GetModelId(AgentUserSecurityID: Guid): Code[30]: gets the model ID of the agent.
• procedure GetModelName(AgentUserSecurityID: Guid): Text[70]: gets the model name of the agent.

You can use these methods when defining your Agents in AL code, for example from your install codeunit:

Now some personal consideration on this change:

You should use GPT-5.3-chat for every task that requires conversation, brainstorming and tasks where you want a natural human-like interaction. GPT-4.1-latest is instead ideal when dealing with heavy tasks, complex data parsing, or workloads that require the model to hold huge volumes of reference documentation.

Microsoft is always a lot conservative on releasing AI models for Business Central, but I think that they can rethink soon on GPT-5.3-chat and instead open also to the new GPT-5.5-chat.

GPT-5.5-chat is now the OpenAI’s default conversational model, offering massive improvements in accuracy and a faster “time-to-first-token” than GPT-5.3-chat. It is significantly more concise, making it better for everyday tasks.

GPT-5.5-chat-latest has also significant reductions in hallucinations, especially in domains where accuracy matters most. According to OpenAI, the new model produces 52.5% fewer hallucinations and reduces hallucinated claims by 37.3% on conversations previously flagged for factual errors when compared to GPT-5.3-chat.

This is now also the default chat model in Microsoft Foundry, so why not using it too?

Original Post https://demiliani.com/2026/06/01/dynamics-365-business-central-new-model-choice-in-agent-definition/