---
id: post/demiliani-com/13814
type: post
title: "Dynamics 365 Business Central: new model choice in Agent definition."
summary: Business Central 28.1 introduces GPT-5.3-chat as the default AI model for Agents and Managed AI service, with a new UI switcher and AL methods allowing administrators to select between available models or use Auto mode. The post discusses model selection guidance and suggests Microsoft consider supporting GPT-5.5-chat for improved accuracy and hallucination reduction.
tier: community
language: en
tags:
  - ai models
  - agents
  - gpt-5.3-chat
  - model selection
  - al development
  - managed ai service
system: copilot
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  by: opus
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    url: https://demiliani.com/2026/06/01/dynamics-365-business-central-new-model-choice-in-agent-definition/
    title: "Dynamics 365 Business Central: new model choice in Agent definition."
    date: "2026-06-01"
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  - kind: blog
    url: https://demiliani.com/2026/06/01/dynamics-365-business-central-new-model-choice-in-agent-definition/
    title: "Dynamics 365 Business Central: new model choice in Agent definition."
    date: "2026-06-01"
    commit: null
    t: null
    quote: GTP-5.3-chat is now the default AI model used by Microsoft on Agents and Managed AI service.
  - kind: blog
    url: https://demiliani.com/2026/06/01/dynamics-365-business-central-new-model-choice-in-agent-definition/
    title: "Dynamics 365 Business Central: new model choice in Agent definition."
    date: "2026-06-01"
    commit: null
    t: null
    quote: The new switcher permits you to choose the model that the agent will uses to complete tasks.
  - kind: blog
    url: https://demiliani.com/2026/06/01/dynamics-365-business-central-new-model-choice-in-agent-definition/
    title: "Dynamics 365 Business Central: new model choice in Agent definition."
    date: "2026-06-01"
    commit: null
    t: null
    quote: You should use GPT-5.3-chat for every task that requires conversation, brainstorming and tasks where you want a natural human-like interaction.
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post_id: "13814"
source_id: demiliani-com
source_name: Stefano Demiliani
url: https://demiliani.com/2026/06/01/dynamics-365-business-central-new-model-choice-in-agent-definition/
published_at: "2026-06-01T07:30:02.000Z"
author: Stefano Demiliani
full_text: false
words: 438
quotes:
  - text: GTP-5.3-chat is now the default AI model used by Microsoft on Agents and Managed AI service.
    why_it_matters: Establishes the key change in version 28.1 that affects how agents operate by default
  - text: The new switcher permits you to choose the model that the agent will uses to complete tasks.
    why_it_matters: Describes the main feature allowing administrators to configure model selection for agents
  - text: You should use GPT-5.3-chat for every task that requires conversation, brainstorming and tasks where you want a natural human-like interaction.
    why_it_matters: Provides practical guidance on when to use each model based on task requirements
code_objects_mentioned:
  - codeunit Agent
systems:
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versions_mentioned:
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---

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

[Read the post](https://demiliani.com/2026/06/01/dynamics-365-business-central-new-model-choice-in-agent-definition/) · Stefano Demiliani (Stefano Demiliani, MVP) · 2026-06-01 · 438 words · tier community · reviewed (checked by Opus)

> Business Central 28.1 introduces GPT-5.3-chat as the default AI model for Agents and Managed AI service, with a new UI switcher and AL methods allowing administrators to select between available models or use Auto mode. The post discusses model selection guidance and suggests Microsoft consider supporting GPT-5.5-chat for improved accuracy and hallucination reduction.

## Key points

- GPT-5.3-chat is now the default model for Agents and Managed AI service in version 28.1, with a new model switcher on the Agents page
- Available AI models can be selected via UI or programmatically through new Agent codeunit methods: SetModelId, SetModelIdToAuto, GetModelId, and GetModelName
- GPT-5.3-chat suits conversational and brainstorming tasks, while GPT-4.1-latest is better for complex data parsing and heavy workloads with large reference documentation
- GPT-5.5-chat is recommended as a future option due to 52.5% fewer hallucinations and faster response times compared to GPT-5.3-chat

## Quotes

- "GTP-5.3-chat is now the default AI model used by Microsoft on Agents and Managed AI service." (Establishes the key change in version 28.1 that affects how agents operate by default)
- "The new switcher permits you to choose the model that the agent will uses to complete tasks." (Describes the main feature allowing administrators to configure model selection for agents)
- "You should use GPT-5.3-chat for every task that requires conversation, brainstorming and tasks where you want a natural human-like interaction." (Provides practical guidance on when to use each model based on task requirements)

## AL objects mentioned

As named in the post. A name that matches one object page by exact type and name links to it; the others stay as named.

- [codeunit 4321 "Agent"](../../objects/codeunit/4321.md)

## Context

- Features: AI model switcher for Agents, SetModelId method, SetModelIdToAuto method, GetModelId method, GetModelName method, Auto model mode, GPT-5.3-chat default model, GPT-4.1-latest support
- Versions: 28.1

Source: Stefano Demiliani, community blog. Summary, key points and quotes are derived (CONTENT-NOTICE.md); read the original for the full text.