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Which MLflow judges need ground truth?

The built-in judges that need expected answers, and those that don't.

From Ultra Transcenders DBX-GENAI by Tony Rough (coming December 2026)

Built-in LLM judges are predefined scorers running on Databricks-hosted LLMs. The dividing line between them is whether expectations must be supplied, since curated labels cost time to gather.

Judge Arguments Needs ground truth Evaluates
RelevanceToQuery inputs, outputs No Response directly relevant to the request
RetrievalRelevance inputs, outputs No Retrieved context relevant to the request
Safety inputs, outputs No Free from harmful, offensive or toxic material
RetrievalGroundedness inputs, outputs No Response grounded in the context
Guidelines inputs, outputs No Meets stated natural-language criteria
ToolCallEfficiency inputs, outputs No Tool calls free of redundancy
Correctness inputs, outputs, expectations Yes Response correct against ground truth
RetrievalSufficiency inputs, outputs, expectations Yes Context contains all ground truth facts
ToolCallCorrectness inputs, outputs, expectations Yes Tool calls and arguments correct
ExpectationsGuidelines inputs, outputs, expectations No, but needs guidelines in expectations Meets per-example criteria

A sensible pattern follows from the table. A team with no labels can begin with relevance, groundedness and safety, then add Correctness and RetrievalSufficiency as human labels accumulate. The cookbook confirms this order, advising a start with questions alone and adding ground truth over time. Figure 14.1 sorts the judges by what they need.

Six judges need no ground truth: RelevanceToQuery, RetrievalRelevance, Safety, RetrievalGroundedness, Guidelines and ToolCallEfficiency. Correctness, RetrievalSufficiency and ToolCallCorrectness need it, and ExpectationsGuidelines does not but needs guidelines in expectations.
Figure 14.1: Built-in judges sorted by whether they need ground truth.

Reserved keys in expectations connect labels to judges.

Key Used by Holds
expected_facts Correctness List of facts that should appear
expected_response Correctness Exact or similar expected output
guidelines ExpectationsGuidelines Natural-language rules for the row
expected_retrieved_context document_recall scorer Documents that should be retrieved

The older cookbook table maps onto this list and adds measurement types: chunk_relevance and groundedness as judges needing no ground truth, context_sufficiency and correctness as judges needing it, and document_recall as a deterministic metric needing ground truth. Token counts and latency_seconds are deterministic. Collect both retrieval and response metrics, since an application can answer poorly with the right context or well despite faulty retrieval.

Judge models can be changed with the model argument in the form <provider>:/<model-name>, for example Correctness(model="databricks:/databricks-gpt-5-mini"). Judges may use third-party services. With cross-Geo processing disabled they stay in the workspace’s Geo and can return a geo-restriction error. With Partner-powered AI features disabled they need a customer-provided model.

Common trap: RetrievalGroundedness needs human-labelled answers because it checks facts - it compares the response with the retrieved context, not with ground truth. RetrievalSufficiency is the retrieval judge that needs expectations.

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This note is one section of Ultra Transcenders DBX-GENAI: Databricks Generative AI Engineer Associate, an independent study guide that explains every topic the exam covers by technology, with comparison tables, diagrams and the common traps, plus a glossary linked to the Databricks documentation.

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