awesome-copilot/plugins/phoenix/skills/phoenix-tracing/references/span-evaluator.md

EVALUATOR Spans

Purpose

EVALUATOR spans represent quality assessment operations (answer relevance, faithfulness, hallucination detection).

Required Attributes

Attribute	Type	Description	Required
openinference.span.kind	String	Must be "EVALUATOR"	Yes

Common Attributes

Attribute	Type	Description
input.value	String	Content being evaluated
output.value	String	Evaluation result (score, label, explanation)
metadata.evaluator_name	String	Evaluator identifier
metadata.score	Float	Numeric score (0-1)
metadata.label	String	Categorical label (relevant/irrelevant)

Example: Answer Relevance

{
  "openinference.span.kind": "EVALUATOR",
  "input.value": "{\"question\": \"What is the capital of France?\", \"answer\": \"The capital of France is Paris.\"}",
  "input.mime_type": "application/json",
  "output.value": "0.95",
  "metadata.evaluator_name": "answer_relevance",
  "metadata.score": 0.95,
  "metadata.label": "relevant",
  "metadata.explanation": "Answer directly addresses the question with correct information"
}

Example: Faithfulness Check

{
  "openinference.span.kind": "EVALUATOR",
  "input.value": "{\"context\": \"Paris is in France.\", \"answer\": \"Paris is the capital of France.\"}",
  "input.mime_type": "application/json",
  "output.value": "0.5",
  "metadata.evaluator_name": "faithfulness",
  "metadata.score": 0.5,
  "metadata.label": "partially_faithful",
  "metadata.explanation": "Answer makes unsupported claim about Paris being the capital"
}