# Grab Bench: Evaluating AI on Grab-shaped production work

[Grab](https://yomu.fyi/company/grab) · Christian Coffrant · Aug 12, 2026

## Summary

AI models evaluated on internal tasks often produce subtly plausible errors, such as altering metric definitions in SQL queries or missing hidden stateful invariants in code patches. To address this, Grab built Grab Bench, a configurable evaluation harness that executes model providers through specialized task plugins. The platform evaluates synthetic or redacted datasets that preserve production constraints across domains like query generation, tool use, passenger-profile reasoning, and agentic coding. By recording granular row-level outputs with deterministic scorers and LLM judges, the harness exposes failure modes rather than relying solely on aggregate leaderboards.

## Takeaways

- Grab Bench utilizes synthetic datasets paired with deterministic scorers to test strict domain contracts—such as ontology checks, evidence IDs, and hidden workspace tests—without exposing production data.
- The evaluation harness tests for shortcuts by running weak baselines like cite-all-evidence and visible-test-only agents to ensure the benchmark cannot be trivially passed.
- Evaluation artifacts are divided into open teaching artifacts for understanding the harness and restricted certification artifacts with hidden splits to prevent prompt overfitting.

**Tags:** [LLMs](https://yomu.fyi/topic/llm), [Machine Learning](https://yomu.fyi/topic/machine-learning), [Reliability](https://yomu.fyi/topic/reliability), [Testing](https://yomu.fyi/topic/testing)

[Read original post](https://engineering.grab.com/grab-bench-evaluating-ai)