agent-evaluation

name	agent-evaluation
description	Evaluate GenAI agent task execution using LLM-as-judge. Produces structured scores (0-5), feedback, and improvement recommendations.
metadata	{"author":"opencode-reflection-plugin","version":"1.0"}

Agent Evaluation Skill

Evaluate AI agent task execution using world-class LLM-as-judge patterns from DeepEval, RAGAS, and G-Eval frameworks.

Output Format

Evaluation results are saved to evals/results/eval-${yyyy-mm-dd-hh-mm}-${commit_id}.md

Results Table

Task Input	Agent Output	Reflection Input	Reflection Output	Score	Verdict	Feedback
Create hello.js...	I've created hello.js with...	Task: Create hello.js Agent Output: ...	Task complete	5/5	COMPLETE	Agent produced output; Found completion indicators
Fix the bug...	I found the issue and...	Task: Fix bug Agent Output: ...	(none)	3/5	PARTIAL	Agent produced output; Missing reflection

Run Evaluation

# Run E2E evaluation
npx tsx eval.ts

# Or via npm
npm run eval:e2e

# Output saved to: evals/results/eval-2026-01-28-12-30-abc1234.md

---

Evaluation Rubric (0-5)

Score	Verdict	Criteria
5	COMPLETE	Task fully accomplished. All requirements met. Optimal execution.
4	MOSTLY_COMPLETE	Task done with minor issues. 1-2 suboptimal steps.
3	PARTIAL	Core objective achieved but significant gaps or errors.
2	ATTEMPTED	Progress made but failed to complete. Correct intent, wrong execution.
1	FAILED	Wrong approach or incorrect result.
0	NO_ATTEMPT	No meaningful progress. Crashed or no output.

Pass threshold: >= 3 (development), >= 4 (production)

---

Evaluation Prompt Template

Use this prompt for LLM-as-judge evaluation:

You are an expert evaluator assessing AI agent task completion.

## Original Task
{{task}}

## Execution Trace
{{trace}}

## Final Output
{{output}}

## Evaluation Criteria
1. Was the core objective achieved?
2. Were appropriate tools selected?
3. Were tool arguments correct?
4. Was execution efficient (minimal steps)?
5. Is the final output accurate and complete?

## Scoring Rubric
- 5: COMPLETE - All requirements met perfectly
- 4: MOSTLY_COMPLETE - Minor issues only
- 3: PARTIAL - Core done but significant gaps
- 2: ATTEMPTED - Progress made but failed
- 1: FAILED - Wrong approach or result
- 0: NO_ATTEMPT - No meaningful progress

## Instructions
1. Analyze the execution step-by-step
2. Identify specific issues or strengths
3. Score using the rubric
4. Provide actionable recommendations

## Response Format (JSON only)
{
  "reasoning": "<step-by-step analysis>",
  "score": <0-5>,
  "verdict": "<COMPLETE|MOSTLY_COMPLETE|PARTIAL|ATTEMPTED|FAILED|NO_ATTEMPT>",
  "feedback": "<1-2 sentence summary>",
  "recommendations": ["<improvement 1>", "<improvement 2>"]
}

---

Quick Evaluation Playbook

Step 1: Extract Data

# Get task from session
TASK=$(cat .reflection/session_*.json | jq -r '.task' | head -1)

# Get execution trace (last 20 messages)
TRACE=$(opencode session messages --limit 20 --format json)

# Get final output
OUTPUT=$(opencode session messages --last --format text)

Step 2: Run Evaluation

# Using promptfoo (recommended)
cd evals && npx promptfoo eval \
  -c agent-eval.yaml \
  --var task="$TASK" \
  --var trace="$TRACE" \
  --var output="$OUTPUT" \
  -o results/eval-$(date +%s).json

# Or using direct API call
curl -X POST "https://api.openai.com/v1/chat/completions" \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-4o-mini",
    "messages": [{"role": "user", "content": "<EVAL_PROMPT>"}],
    "response_format": {"type": "json_object"}
  }' | jq '.choices[0].message.content | fromjson'

Step 3: Parse Results

# Extract score and feedback
cat results/eval-*.json | jq '{
  score: .score,
  verdict: .verdict,
  feedback: .feedback,
  recommendations: .recommendations
}'

---

Metrics Reference

Core Agent Metrics

Metric	Type	Description
Task Completion	0-5	Overall goal achievement
Tool Correctness	binary	Right tools selected
Argument Accuracy	0-1	Tool arguments correct
Step Efficiency	0-1	Minimal steps to goal

Composite Scores

overall_score = (
  task_completion * 0.5 +
  tool_correctness * 0.2 +
  argument_accuracy * 0.2 +
  step_efficiency * 0.1
)

---

promptfoo Config Example

Create evals/agent-eval.yaml:

description: Agent task completion evaluation

prompts:
  - file://prompts/agent-evaluation.txt

providers:
  - id: azure:gpt-4.1-mini
    config:
      apiHost: eastus.api.cognitive.microsoft.com
      deployment_id: gpt-4.1-mini

defaultTest:
  assert:
    - type: is-json
    - type: javascript
      value: output.score >= 0 && output.score <= 5

tests:
  - vars:
      task: "Create a hello.js file that prints Hello World"
      trace: |
        1. Agent reads current directory
        2. Agent creates hello.js with console.log("Hello World")
        3. Agent confirms file created
      output: "Created hello.js with console.log('Hello World')"
    assert:
      - type: javascript
        value: JSON.parse(output).score >= 4

---

Integration with Reflection Plugin

The reflection plugin uses this evaluation pattern internally:

// reflection-3.ts - simplified evaluation flow
async function evaluateTask(sessionId: string): Promise<Evaluation> {
  const task = extractInitialTask(messages)
  const trace = formatExecutionTrace(messages)
  const output = extractFinalOutput(messages)
  
  const response = await llm.chat({
    messages: [{ role: "user", content: buildEvalPrompt(task, trace, output) }],
    response_format: { type: "json_object" }
  })
  
  return JSON.parse(response.content)
}

---

Benchmarks

Standard Test Cases

#	Task	Expected Score	Notes
1	Create file	5	Simple, single tool
2	Multi-file refactor	4+	Multiple edits
3	Debug test failure	3+	Iterative process
4	Research question	4+	Read-only, synthesis

Running Benchmarks

# Run full benchmark suite
npm run eval

# Run specific benchmark
npm run eval:judge

# View results
npm run eval:view

---

Best Practices

1. Always include reasoning - Makes debugging possible
2. Use structured JSON output - Parse reliably
3. Score consistently - Same rubric across all evals
4. Track over time - Catch regressions
5. Calibrate with humans - Validate judge accuracy periodically
6. Separate outcome vs process - Score both what and how

---

Troubleshooting

Issue	Cause	Solution
Score always 5	Prompt too lenient	Add explicit failure criteria
Score always low	Rubric too strict	Calibrate with human evals
JSON parse error	LLM not following format	Add response_format constraint
Inconsistent scores	Ambiguous criteria	Make rubric more specific
Slow evaluation	Large trace	Truncate to last N messages