Introducing OpenAI's newest chat model in Microsoft Foundry

2026-05-05 · Source: Microsoft Foundry Blog articles · Field: Technology & Digital — Artificial Intelligence & Machine Learning, Software Development & Engineering · Depth: Intermediate, medium

Summary

Microsoft Foundry is rolling out OpenAI's new GPT-5.5 Instant model, branded as GPT-chat-latest, starting May 05, 2026. This model, built upon GPT-5.4 and GPT-5.3-chat, significantly improves factual accuracy, tool calling, and response efficiency. OpenAI reports a 52.5% reduction in hallucinations and a 37.3% decrease in hallucinated claims compared to GPT-5.3-chat. Benchmarks show gains in scientific chart reasoning (CharXiv-reasoning: 81.6), expert multimodal reasoning (MMMU-Pro: 76.0), PhD-level science questions (GPQA: 85.6), and competition math (AIME 2025: 81.2). GPT-chat-latest also produces 25–30% fewer words while maintaining quality, leading to lower output token costs and cleaner responses. It enhances tool interaction, search, and context handling, making it suitable for multi-turn assistants and agentic systems.

Key takeaway

For CTOs and VPs of Engineering deploying conversational AI, GPT-chat-latest offers a more reliable and cost-effective solution for multi-turn assistants and agentic systems. Its reduced hallucinations and improved tool calling capabilities make it particularly suitable for regulated industries like clinical decision support or legal research. You should evaluate this model for applications requiring high factual accuracy and efficient, structured outputs to reduce post-processing and operational costs.

Key insights

GPT-chat-latest improves factual accuracy, tool calling, and response efficiency for production AI deployments.

Principles

• Reduced hallucinations enhance reliability for regulated workloads.
• Efficient outputs lower costs and simplify UI integration.
• Improved tool orchestration supports complex agentic workflows.

Method

The model integrates advancements from GPT-5.4 and GPT-5.3-chat, focusing on reducing verbosity, enhancing tool invocation logic, and refining search/context handling.

In practice

• Deploy for customer support virtual agents.
• Utilize for retail shopping assistants.
• Implement in technician-facing field service tools.

Topics

• GPT-chat-latest
• Microsoft Foundry
• Factual Accuracy
• Tool Calling
• Retrieval-Augmented Generation

Best for: CTO, VP of Engineering/Data, Director of AI/ML, AI Engineer, Machine Learning Engineer, MLOps Engineer

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Editorial summary, takeaway, and curation by AIssential. Original article published by Microsoft Foundry Blog articles.