RoboPhD: Self-Improving Text-to-SQL Through Autonomous Agent Evolution
Andrew Borthwick, Stephen Ash
TL;DR
RoboPhD demonstrates that AI agents can autonomously conduct the research cycle—hypothesis generation, experimentation, and refinement—to improve Text-to-SQL performance starting from a minimal baseline. It achieves this through a two-artifact architecture (offline database analysis tool and online SQL-generation instructions) coupled with an ELO-based evolutionary loop that cross-pollinates techniques from top performers. The system yields meaningful gains across model tiers, most notably a substantial improvement on cheaper models, and achieves 73.67% accuracy on the BIRD test set, illustrating practical deployment potential. By open-sourcing the framework and relying on minimal human domain knowledge, RoboPhD suggests a path toward scalable autonomous capability development beyond Text-to-SQL.
Abstract
We present RoboPhD, a system where AI agents autonomously conduct research to improve Text-to-SQL performance. RoboPhD implements a closed-loop evolution cycle with two coordinated components: a SQL Generation agent composed of a database analysis script and SQL generation instructions, and an Evolution agent that designs new versions based on performance feedback. Central to the framework is an ELO-based selection mechanism enabling survival-of-the-fittest dynamics while handling non-transitivity in performance. Starting from a naive 70-line baseline, RoboPhD evolves agents through iterative cross-pollination, discovering effective techniques without any external guidance on the Text-to-SQL domain. Our best agent, evolved to 1500 lines over 18 iterations, autonomously discovered strategies such as size-adaptive database analysis that adjusts depth based on schema complexity and SQL generation patterns for column selection, evidence interpretation, and aggregation. Evolution provides the largest gains on cheaper models: while we improve by 2.3 points over a strong Claude Opus 4.5 naive baseline, we show an improvement of 8.9 points over the weaker Claude Haiku model. This enables 'skip a tier' deployment: evolved Haiku exceeds naive Sonnet accuracy, and evolved Sonnet exceeds naive Opus, both at lower cost. The full system achieves 73.67% accuracy on the BIRD test set, demonstrating that AI can autonomously build a strong agentic system with only a trivial human-provided starting point.
