client.spans namespace. Spans are automatically created when you run prompts or use run_local(), providing visibility into LLM usage, performance, and costs.
Terminology: A span represents a single LLM call. Multiple spans can be grouped into a trace (session) using the
trace_id parameter.Async Variants
Available Methods
List
Get spans with filters and pagination
Get
Retrieve full details of a single span
Evaluate
Submit evaluations for spans
Types
Span
ListSpansOptions
EvaluateOptions
EvaluateResult
Eval Constant
Use theEval constant for binary evaluations:

