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

RERANKER Spans

Purpose

RERANKER spans represent reordering of retrieved documents (Cohere Rerank, cross-encoder models).

Required Attributes

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

Attribute Reference

Reranker Parameters

Attribute	Type	Description
reranker.model_name	String	Reranker model identifier
reranker.query	String	Query used for reranking
reranker.top_k	Integer	Number of documents to return

Input Documents

Attribute Pattern	Type	Description
reranker.input_documents.{i}.document.id	String	Input document ID
reranker.input_documents.{i}.document.content	String	Input document content
reranker.input_documents.{i}.document.score	Float	Original retrieval score
reranker.input_documents.{i}.document.metadata	String (JSON)	Document metadata

Output Documents

Attribute Pattern	Type	Description
reranker.output_documents.{i}.document.id	String	Output document ID (reordered)
reranker.output_documents.{i}.document.content	String	Output document content
reranker.output_documents.{i}.document.score	Float	New reranker score
reranker.output_documents.{i}.document.metadata	String (JSON)	Document metadata

Score Comparison

Input scores (from retriever) vs. output scores (from reranker):

{
  "reranker.input_documents.0.document.id": "doc_A",
  "reranker.input_documents.0.document.score": 0.7,
  "reranker.input_documents.1.document.id": "doc_B",
  "reranker.input_documents.1.document.score": 0.9,
  "reranker.output_documents.0.document.id": "doc_B",
  "reranker.output_documents.0.document.score": 0.95,
  "reranker.output_documents.1.document.id": "doc_A",
  "reranker.output_documents.1.document.score": 0.85
}

In this example:

• Input: doc_B (0.9) ranked higher than doc_A (0.7)
• Output: doc_B still highest but both scores increased
• Reranker confirmed retriever's ordering but refined scores

Examples

Complete Reranking Example

{
  "openinference.span.kind": "RERANKER",
  "reranker.model_name": "cohere-rerank-v2",
  "reranker.query": "What is machine learning?",
  "reranker.top_k": 2,
  "reranker.input_documents.0.document.id": "doc_123",
  "reranker.input_documents.0.document.content": "Machine learning is a subset...",
  "reranker.input_documents.1.document.id": "doc_456",
  "reranker.input_documents.1.document.content": "Supervised learning algorithms...",
  "reranker.input_documents.2.document.id": "doc_789",
  "reranker.input_documents.2.document.content": "Neural networks are...",
  "reranker.output_documents.0.document.id": "doc_456",
  "reranker.output_documents.0.document.content": "Supervised learning algorithms...",
  "reranker.output_documents.0.document.score": 0.95,
  "reranker.output_documents.1.document.id": "doc_123",
  "reranker.output_documents.1.document.content": "Machine learning is a subset...",
  "reranker.output_documents.1.document.score": 0.88
}