Evaluation Failure Patterns & Fixes

Common failure modes observed in GenAI agent evaluations, mapped to their root causes and concrete fixes. Metric IDs below are the unversioned form (the SDK auto-resolves them to the latest version); see metric_registry.md for the full catalog.

For the compact failure → fix mapping, see the What to fix when scores fail table in SKILL.md.

Metric-Specific Failures

Low hallucination or grounding Score

Symptom: Agent generates plausible-sounding but factually incorrect information, or doesn't use the provided context.

Root causes:

• System prompt lacks explicit grounding instructions
• Retrieved context not passed into the prompt
• Agent ignores context in favor of parametric knowledge

Fixes:

1. Add to system prompt: "Base ALL answers strictly on the provided context. If the context doesn't contain the answer, say 'I don't have that information.'"
2. Verify context is actually injected into the prompt (check tool responses).
3. Add temperature=0 or lower temperature to reduce creative generation.

Low general_quality or text_quality

Symptom: Agent responses are poorly structured, unclear, or unhelpful.

Root causes:

• System prompt too vague
• Agent over-explains or under-explains
• Missing output format instructions

Fixes:

1. Add explicit format instructions: "Respond concisely in 2-3 sentences."
2. Add few-shot examples in the system prompt.
3. Review rubric verdicts for specific quality dimensions that scored low.

Low tool_use_quality (single-turn) or multi_turn_tool_use_quality

Symptom: Agent calls the wrong tool, uses wrong parameters, or doesn't call tools when it should.

Root causes:

• Tool descriptions are ambiguous
• Multiple tools have overlapping functionality
• Function declaration parameter schemas are incomplete

Fixes:

1. Make tool description fields precise and mutually exclusive.
2. Add parameter descriptions and constraints to FunctionDeclaration.
3. Add to system prompt: "Always use {tool_name} when the user asks about {specific_topic}."
4. For granular diagnosis of parameter mismatches, add a computation metric like tool_parameter_kv_match alongside the rubric metric.

Low multi_turn_trajectory_quality

Symptom: Agent takes suboptimal paths through a conversation — unnecessary tool calls, redundant questions, or wrong delegation order.

Root causes:

• Router agent lacks clear delegation rules
• Agent retries failed operations without adaptation
• Missing escalation logic

Fixes:

1. Add explicit routing rules: "Route to {agent} when {condition}."
2. Add retry limits: "If {tool} fails twice, inform the user and suggest alternatives."
3. Review the trajectory events in agent_data to identify the specific turn where the agent deviated.

Low multi_turn_task_success

Symptom: Agent engages in conversation but doesn't complete the user's actual goal.

Root causes:

• Agent gets sidetracked by follow-up questions
• Missing confirmation/completion step
• Agent doesn't track task state across turns

Fixes:

1. Add to system prompt: "Always confirm task completion with the user before ending the conversation."
2. Implement explicit task tracking in agent logic.
3. Verify max_turn in user simulator is sufficient for the task complexity.

Low safety

Symptom: Agent generates unsafe content or complies with harmful requests.

Root causes:

• System prompt lacks safety constraints
• Agent follows user instructions too literally
• Missing refusal logic for out-of-scope requests

Fixes:

1. Add safety guardrails: "Never provide medical/legal/financial advice. Redirect to appropriate professionals."
2. Add refusal patterns: "If the user asks for {harmful_category}, politely decline."
3. Use safety alongside domain-specific LLMMetric safety checks.

Structural Failures

is_infra_error: true

Symptom: Eval case fails with infrastructure error, not a quality issue.

Root causes:

• API quota exceeded
• Network timeout
• Model endpoint temporarily unavailable

Fix: Re-run the evaluation. If persistent, check quota and endpoint health.

Timeout

Symptom: Evaluation times out before completing.

Root causes:

• Dataset too large for a single API call
• Complex custom metric code takes too long
• Judge model sampling count too high

Fixes:

1. Reduce dataset size or batch into smaller chunks.
2. Optimize custom metric code (avoid network calls in evaluate()).
3. Reduce judge_model_sampling_count (default 1, max 32).

KeyError in Custom Metric

Symptom: Custom function crashes with missing field.

Root cause: Metric function expects a field not present in the eval case.

Fix: Check available fields in the instance dict. For agent-trace datasets, the standard top-level field is agent_data (a structured turns/events object) — the agent's final response lives inside it. Flat placeholders like {response} only resolve in the DataFrame eval path. Always use .get() with defaults.

Analysis Workflow

When eval results show failures:

1. Start with summary_metrics — identify which metrics scored lowest. Use scripts/inspect_results.py to render the table.
2. Drill into eval_case_results — find specific failing cases. Use scripts/inspect_results.py --failing-only to filter.
3. For 10+ failures on the same metric — run the Error Analysis service (client.evals.generate_loss_clusters) for multi_turn_task_success or multi_turn_tool_use_quality to cluster failures into L1/L2 themes instead of skimming case-by-case.
4. Read rubric_verdicts — understand why the judge scored low.
5. Cross-reference with agent_data — find the exact turn/event that caused the failure.
6. Identify the pattern — is it a prompt issue, tool issue, or data issue?
7. Apply the targeted fix — from the table above or the SKILL.md What to fix when scores fail table.
8. Re-run and compare — use scripts/compare_results.py to verify the fix improved the target metric without regressing others.