State of AI Agents 2025: Technical Building Blocks and Real-World Applications

Author here. I wrote this piece because I couldn't find a comprehensive technical overview that connected the foundations of AI agents (memory systems, planning capabilities, tool integration) with their current real-world applications and limitations. Most existing articles either focused purely on theoretical aspects or just listed use cases without diving into the technical architecture behind them. I synthesized findings from dozens of research papers and articles to create this overview.