Universal Attributes

This document covers attributes that can be used on any span kind in OpenInference.

Overview

These attributes can be used on any span kind to provide additional context, tracking, and metadata.

Input/Output

Why Capture I/O?

Always capture input/output for evaluation-ready spans:

• Phoenix evaluators (faithfulness, relevance, Q&A correctness) require input.value and output.value
• Phoenix UI displays I/O prominently in trace views for debugging
• Enables exporting I/O for creating fine-tuning datasets
• Provides complete context for analyzing agent behavior

Example attributes:

{
  "openinference.span.kind": "CHAIN",
  "input.value": "What is the weather?",
  "input.mime_type": "text/plain",
  "output.value": "I don't have access to weather data.",
  "output.mime_type": "text/plain"
}

See language-specific implementation:

• TypeScript: instrumentation-manual-typescript.md
• Python: instrumentation-manual-python.md

Session and User Tracking

Example:

{
  "openinference.span.kind": "LLM",
  "session.id": "session_abc123",
  "user.id": "user_xyz789"
}

Metadata

Example:

{
  "openinference.span.kind": "LLM",
  "metadata": "{\"environment\": \"production\", \"model_version\": \"v2.1\", \"cost_center\": \"engineering\"}"
}