---

name: agentv-eval-builder description: Create and maintain AgentV YAML evaluation files for testing AI agent performance. Use this skill when creating new eval files, adding eval cases, or configuring custom evaluators (code validators or LLM judges) for agent testing workflows.

AgentV Eval Builder

Schema Reference

• Schema: references/eval-schema.json (JSON Schema for validation and tooling)
• Format: YAML or JSONL (see below)
• Examples: references/example-evals.md

Feature Reference

• Rubrics: references/rubric-evaluator.md - Structured criteria-based evaluation
• Composite Evaluators: references/composite-evaluator.md - Combine multiple evaluators
• Tool Trajectory: references/tool-trajectory-evaluator.md - Validate agent tool usage
• Structured Data + Metrics: references/structured-data-evaluators.md - field_accuracy, latency, cost
• Custom Evaluators: references/custom-evaluators.md - Code and LLM judge templates
• Batch CLI: references/batch-cli-evaluator.md - Evaluate batch runner output (JSONL)
• Compare: references/compare-command.md - Compare evaluation results between runs

Structure Requirements

• Root level: description (optional), execution (with target), evalcases (required)
• Eval case fields: id (required), expected_outcome (required), input_messages or input (required)
• Optional fields: expected_messages (or expected_output), conversation_id, rubrics, execution
• expected_messages is optional - omit for outcome-only evaluation where the LLM judge evaluates based on expected_outcome criteria alone
• Message fields: role (required), content (required)
• Message roles: system, user, assistant, tool

Input/Output Shorthand (Aliases)

For simpler eval cases, use shorthand aliases instead of the verbose input_messages and expected_messages:

String shorthand:

Copyevalcases:
  - id: simple-test
    expected_outcome: Correct answer
    input: "What is 2+2?"                    # Expands to [{role: user, content: "..."}]
    expected_output: "The answer is 4"       # Expands to [{role: assistant, content: "..."}]

Object shorthand (for structured output validation):

Copyevalcases:
  - id: structured-output
    expected_outcome: Risk assessment
    input: "Analyze this transaction"
    expected_output:                          # Expands to assistant message with object content
      riskLevel: High
      confidence: 0.95

Array syntax still works for multi-message conversations:

Copyinput:
  - role: system
    content: "You are a calculator"
  - role: user
    content: "What is 2+2?"

Precedence: Canonical names (input_messages, expected_messages) take precedence when both are specified.

• Content types: text (inline), file (relative or absolute path)
• Attachments (type: file) should default to the user role
• File paths: Relative (from eval file dir) or absolute with "/" prefix (from repo root)

JSONL Format

For large-scale evaluations, use JSONL (one eval case per line) instead of YAML:

dataset.jsonl:

Copy{"id": "test-1", "expected_outcome": "Correct answer", "input_messages": [{"role": "user", "content": "What is 2+2?"}]}
{"id": "test-2", "expected_outcome": "Clear explanation", "input_messages": [{"role": "user", "content": [{"type": "text", "value": "Review this"}, {"type": "file", "value": "./code.py"}]}]}

dataset.yaml (optional sidecar for defaults):

Copydescription: My dataset
dataset: my-tests
execution:
  target: azure_base
evaluator: llm_judge

Benefits: Git-friendly diffs, streaming-compatible, easy programmatic generation. Per-case fields override sidecar defaults. See examples/features/basic-jsonl/ for complete example.

Custom Evaluators

Configure multiple evaluators per eval case via execution.evaluators array.

Code Evaluators

Scripts that validate output programmatically:

Copyexecution:
  evaluators:
    - name: json_format_validator
      type: code_judge
      script: uv run validate_output.py
      cwd: ../../evaluators/scripts

Contract:

• Input (stdin): JSON with question, expected_outcome, reference_answer, candidate_answer, guideline_files, input_files, input_messages, expected_messages, output_messages, trace_summary
• Output (stdout): JSON with score (0.0-1.0), hits, misses, reasoning

Target Proxy: Code evaluators can access an LLM through the target proxy for sophisticated evaluation logic (e.g., Contextual Precision, semantic similarity). Enable with target: {}:

Copyexecution:
  evaluators:
    - name: contextual_precision
      type: code_judge
      script: bun run evaluate.ts
      target: {}           # Enable target proxy (max_calls: 50 default)

RAG Evaluation Pattern: For retrieval-based evals, pass retrieval context via expected_messages.tool_calls:

Copyexpected_messages:
  - role: assistant
    tool_calls:
      - tool: vector_search
        output:
          results: ["doc1", "doc2", "doc3"]

TypeScript evaluators: Keep .ts source files and run them via Node-compatible loaders such as npx --yes tsx so global agentv installs stay portable. See references/custom-evaluators.md for complete templates, target proxy usage, and command examples.

Template: See references/custom-evaluators.md for Python and TypeScript templates

LLM Judges

Language models evaluate response quality:

Copyexecution:
  evaluators:
    - name: content_evaluator
      type: llm_judge
      prompt: /evaluators/prompts/correctness.md
      model: gpt-5-chat

Tool Trajectory Evaluators

Validate agent tool usage patterns (requires output_messages with tool_calls from provider):

Copyexecution:
  evaluators:
    - name: research_check
      type: tool_trajectory
      mode: any_order       # Options: any_order, in_order, exact
      minimums:             # For any_order mode
        knowledgeSearch: 2
      expected:             # For in_order/exact modes
        - tool: knowledgeSearch
        - tool: documentRetrieve

See references/tool-trajectory-evaluator.md for modes and configuration.

Multiple Evaluators

Define multiple evaluators to run sequentially. The final score is a weighted average of all results.

Copyexecution:
  evaluators:
    - name: format_check      # Runs first
      type: code_judge
      script: uv run validate_json.py
    - name: content_check     # Runs second
      type: llm_judge

Rubric Evaluator

Inline rubrics for structured criteria-based evaluation:

Copyevalcases:
  - id: explanation-task
    expected_outcome: Clear explanation of quicksort
    input_messages:
      - role: user
        content: Explain quicksort
    rubrics:
      - Mentions divide-and-conquer approach
      - Explains the partition step
      - id: complexity
        description: States time complexity correctly
        weight: 2.0
        required: true

See references/rubric-evaluator.md for detailed rubric configuration.

Composite Evaluator

Combine multiple evaluators with aggregation:

Copyexecution:
  evaluators:
    - name: release_gate
      type: composite
      evaluators:
        - name: safety
          type: llm_judge
          prompt: ./prompts/safety.md
        - name: quality
          type: llm_judge
          prompt: ./prompts/quality.md
      aggregator:
        type: weighted_average
        weights:
          safety: 0.3
          quality: 0.7

See references/composite-evaluator.md for aggregation types and patterns.

Batch CLI Evaluation

Evaluate external batch runners that process all evalcases in one invocation:

Copydescription: Batch CLI evaluation
execution:
  target: batch_cli

evalcases:
  - id: case-001
    expected_outcome: Returns decision=CLEAR
    expected_messages:
      - role: assistant
        content:
          decision: CLEAR
    input_messages:
      - role: user
        content:
          row:
            id: case-001
            amount: 5000
    execution:
      evaluators:
        - name: decision-check
          type: code_judge
          script: bun run ./scripts/check-output.ts
          cwd: .

Key pattern:

• Batch runner reads eval YAML via --eval flag, outputs JSONL keyed by id
• Each evalcase has its own evaluator to validate its corresponding output
• Use structured expected_messages.content for expected output fields

See references/batch-cli-evaluator.md for full implementation guide.

Example

Copydescription: Example showing basic features and conversation threading
execution:
  target: default

evalcases:
  - id: code-review-basic
    expected_outcome: Assistant provides helpful code analysis
    
    input_messages:
      - role: system
        content: You are an expert code reviewer.
      - role: user
        content:
          - type: text
            value: |-
              Review this function:
              
              ```python
              def add(a, b):
                  return a + b
              ```
          - type: file
            value: /prompts/python.instructions.md
    
    expected_messages:
      - role: assistant
        content: |-
          The function is simple and correct. Suggestions:
          - Add type hints: `def add(a: int, b: int) -> int:`
          - Add docstring
          - Consider validation for edge cases