# What is trajectory evaluation?

> Trajectory evaluation (or tool-call evaluation) scores the sequence of steps an agent took—tools chosen, arguments, ordering, and intermediate decisions—not only the final response.

- HTML: https://openlit.io/glossary/trajectory-evaluation
- Markdown: https://openlit.io/glossary/trajectory-evaluation.md

Final-answer grading misses many harness bugs: wrong tool selection, unnecessary retries, stuck loops, or skipped retrieval. Trajectory evals inspect the path.

OpenLIT traces give you the raw trajectory (LLM and tool spans). Pair them with LLM-as-a-judge or programmatic checks to score paths and gate CI when trajectories regress.


## Related

- [Agent evals](https://openlit.io/glossary/agent-evals.md)
- [Agent observability](https://openlit.io/glossary/agent-observability.md)
- Pillar: https://openlit.io/agent-harness-engineering.md