OpenAI o3 Outperforms GPT-5 in Complex Office Tasks Benchmark

A new benchmark called OdysseyBench, developed by researchers at Microsoft and the University of Edinburgh, has revealed surprising results: OpenAI's older o3 model consistently outperforms the newer GPT-5 in complex, multi-day office workflows. The benchmark evaluates AI agents on 602 tasks across Word, Excel, PDF, email, and calendar applications, split into two categories:

• OdysseyBench+: 300 realistic tasks from OfficeBench.
• OdysseyBench-Neo: 302 hand-crafted, highly complex scenarios.

OdysseyBench includes both simple, single-step tasks and complex, long-term office workflows. | Image: Wang et al.

Key Findings

• On OdysseyBench-Neo, o3 achieved a 61.26% success rate, compared to GPT-5's 55.96% and GPT-5-chat's 57.62%.
• For tasks requiring three applications at once, o3 scored 59.06%, while GPT-5 managed only 53.80%.
• On OdysseyBench+, o3 led with 56.2%, outperforming GPT-5 (54.0%) and GPT-5-chat (40.3%).

OpenAI's o3 reasoning model leads the field on OdysseyBench. | Image: Wang et al.

Why o3 Outperforms GPT-5

The researchers suggest that GPT-5-chat performs better on OdysseyBench-Neo due to its focus on dialog-based assistance, while GPT-5 excels in fragmented, non-conversational scenarios. However, the paper does not specify the reasoning settings for GPT-5, leaving room for further evaluation.

Challenges in AI Workflow Automation

AI agents still struggle with:

• Overlooking critical files or steps.
• Using incorrect tools (e.g., creating PDFs before generating text).
• Multi-stage planning across different applications and timeframes.

The findings are particularly relevant as OpenAI aims to develop AI agents capable of prolonged problem-solving. OdysseyBench could become a key benchmark for these long-horizon systems.