GPT-5.5’s Innovative Reasoning Capabilities and Agent Functionality
OpenAI’s GPT-5.5, released on April 23, 2026, achieves a “new class of intelligence for real work” that surpasses the boundaries of conventional LLMs. This new model has the ability to autonomously plan and execute complex multi-step tasks, completing work while traversing between tools.
The most significant feature of GPT-5.5 is its ability to plan, use tools, check work, and overcome ambiguities on its own, even when given “messy multi-part tasks” by users. This eliminates the need for careful management of each step, as was previously required.
(Reference: Introducing GPT-5.5)
Specific Improvements Shown in Performance Benchmarks
GPT-5.5 demonstrates significantly improved performance in multiple technical benchmarks. In Terminal-Bench 2.0, it scores 82.7% (up from GPT-5.4’s 75.1%), and in Expert-SWE (internal evaluation), it scores 73.1% (up from GPT-5.4’s 68.5%).
Notably, it achieves a score of 78.7% in the OSWorld-Verified benchmark, proving its practicality in computer operation tasks. In CyberGym, it records 81.8%, demonstrating advanced capabilities in the field of cybersecurity.
These numbers indicate that GPT-5.5 has reached a practical level not only in language processing but also in actual software operation and task execution.
(Reference: Introducing GPT-5.5)
Balancing Efficiency and Latency
GPT-5.5 achieves both performance improvement and efficiency. According to OpenAI, GPT-5.5 maintains the same per-token latency as GPT-5.4 while providing a much higher level of intelligence.
Furthermore, the number of tokens required to complete the same Codex task is significantly reduced. This means that more work can be done with fewer resources, directly impacting cost efficiency in real-world operations.
This improvement in efficiency counteracts the tendency for large models to be slow, greatly increasing their practicality in serving environments.
(Reference: Introducing GPT-5.5)
Available Implementation Methods
GPT-5.5 is currently available to ChatGPT’s Plus, Pro, Business, and Enterprise users, as well as to Codex users. GPT-5.5 Pro is available to Pro, Business, and Enterprise users in ChatGPT.
Regarding usage via API, OpenAI is closely collaborating with customers on safety and security requirements and has announced that “GPT-5.5 and GPT-5.5 Pro will be available on the API very soon.”
Developers can currently test GPT-5.5’s capabilities in the ChatGPT web interface or Codex environment. For those planning API integration, it is recommended to check OpenAI’s developer documentation for the latest availability information.
(Reference: Introducing GPT-5.5)
Summary
- By utilizing GPT-5.5’s agent functionality, complex multi-step development tasks can be automated, significantly reducing the burden of manual tool switching and progress management
- With performance scores of 82.7% on Terminal-Bench 2.0 and 73.1% on Expert-SWE, code generation, debugging, and system operation accuracy can be improved by 7-8 points compared to previous models
- Achieving the same latency with fewer token consumption increases efficiency, allowing for the reduction of running costs for large-scale code generation and data analysis tasks while maintaining processing speed
- GPT-5.5 can be immediately tried out in ChatGPT Pro or Codex environments, and integrating its agent functionality into existing workflows can improve development productivity