Annotating Agent Trajectories
How to annotate AI agent trajectories step by step, error taxonomies, severity scoring, and trajectory-level success, using Potato's trajectory evaluation.
A trajectory is the full sequence of steps an agent took, its thoughts, tool calls, and observations. Annotating a trajectory means judging the run as a whole and marking where individual steps went wrong, with a category and a severity for each error. Potato annotates agent trajectories step by step with custom rubrics, free and self-hosted, producing the data behind reward models and targeted debugging.
For the feature reference, see Agentic Annotation.
What do you collect when annotating a trajectory?
- Overall outcome: success, partial success, or failure.
- Per-step judgments: for each step, was it correct, unnecessary, or wrong?
- Error categories: why a step was wrong (wrong tool, bad arguments, hallucination, looping, unsafe action…).
- Severity: how bad each error was, often weighted into a score.
How do I set up trajectory evaluation in Potato?
Potato's trajectory_eval type renders each step as a card and attaches a per-step error taxonomy with severity weights:
annotation_schemes:
- annotation_type: trajectory_eval
name: step_evaluation
description: "Evaluate each step for correctness and mark any errors."
steps_key: steps
error_types:
- {name: reasoning, subtypes: [logical_error, factual_error, planning_error]}
- {name: execution, subtypes: [wrong_tool, wrong_args, api_error]}
- {name: safety, subtypes: [harmful_action, data_leak, scope_violation]}
severities:
- {name: minor, weight: -1}
- {name: major, weight: -5}
- {name: critical, weight: -10}
show_score: trueThe severity weights roll up into a trajectory score, so you can rank runs and track regressions across model versions.
How do I design an agent error taxonomy?
The taxonomy is the heart of the task. Keep it small, exhaustive, and mutually exclusive. A practical starting set:
- Reasoning errors: wrong conclusion, ignored evidence, bad plan.
- Execution errors: wrong tool, malformed call, mishandled result.
- Safety errors: unsafe action, out-of-scope behavior, data exposure.
Add a free-text "other" so annotators aren't forced to misfile novel failures, then promote recurring "other" notes into named categories.
Quality considerations
- Agreement on step correctness is usually high; agreement on error category is lower. Measure both, see Inter-Annotator Agreement.
- Long trajectories are fatiguing; cap length or paginate.
- The "first wrong step" is often what matters most for training, see Process Reward Models.
Further reading
- How to Get Reliable Labels on Agent Trajectories, the longer treatment of taxonomy design, step-level agreement, and adjudication.
- How to Evaluate AI Agents
- Process Reward Models
- Evaluating Tool Use