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Phoenix provides pre-built evaluation metrics that can be used out of the box to assess LLM application quality. These metrics are available in both Python and TypeScript and are designed to work seamlessly with Phoenix’s tracing and experiment infrastructure. All LLM evaluation templates are tested against golden datasets and achieve an F1 score of 85% or higher on benchmarks.

LLM Evaluators

LLM evaluators use a judge model to assess the quality of outputs. These are useful for subjective or nuanced evaluations where simple rules don’t suffice.

Faithfulness

Measures whether a response is faithful to (grounded in) the provided context. Detects hallucinations and unsupported claims.

Hallucination

Detects claims in a response that are unsupported by, or contradict, the conversation. The conversation-level counterpart to Faithfulness.

Conciseness

Evaluates whether a response is concise and free of unnecessary content like filler, hedging, and meta-commentary.

Correctness

Evaluates the general correctness of an LLM response.

Retrieval Relevance

Assesses whether externally retrieved information is relevant to the request, from any source: RAG, tools, MCP, or web search.

Tool Selection

Determines whether the correct tool was selected for a given context from the available options.

Tool Invocation

Checks if a tool was invoked correctly with proper arguments, formatting, and safe content.

Tool Response Handling

Evaluates whether an agent correctly processed a tool’s result, including error handling, data extraction, and safe information disclosure.

Refusal

Detects when an LLM refuses, declines, or avoids answering a user query.

User Friction

Detects corrections, retries, frustration, and challenges expressed in a user’s follow-up message.

Toxicity

Detect hateful, demeaning, abusive, or threatening text in model outputs or user inputs.

Code Evaluators

Code evaluators use deterministic logic for evaluation. These are faster, cheaper, and provide consistent results for objective criteria.

Exact Match

Checks if the output exactly matches an expected value. Supports optional normalization.

Matches Regex

Validates that output matches a specified regular expression pattern.

Precision / Recall / F-Score

Computes precision, recall, and F1 scores for comparing predicted vs actual values.
Looking to create custom evaluators? See the Building Custom Evaluators guide.