meta-evaluator 0.3.2

Evaluate LLM-as-a-Judge systems by measuring alignment between judge outputs and human annotations

MetaEvaluator

Evaluate LLM-as-a-Judge systems by measuring alignment between judge outputs with human annotations.

Overview

MetaEvaluator helps you assess LLM judges by:

• 🤖 Running multiple judges (OpenAI, Anthropic, Google, AWS, etc.) using LiteLLM integration
• 👥 Collecting human annotations through a built-in Streamlit interface
• 📊 Computing alignment metrics (Accuracy, Cohen's Kappa, Alt-Test, text/semantic similarity) and generating comprehensive reports with visualizations and statistical analysis

Installation

1. Install the package:

   # Requires Python 3.13+
   pip install meta-evaluator
   

   Optional dependencies:

   pip install meta-evaluator[ui]    # streamlit for human annotation interface
   pip install meta-evaluator[docs]  # mkdocs for documentation
   pip install meta-evaluator[all]   # all optional dependencies
   

   Or install directly from GitHub:

   pip install git+https://github.com/govtech-responsibleai/meta-evaluator
   

2. Set up environment variables: You can either:

   • Copy the .env.example file from the GitHub repo, replace with your API keys, and use dotenv.load_dotenv() in your script
   • Set the environment variables directly in your shell

   See LiteLLM providers documentation for all supported providers.

3. (Optional) For developers: clone the repository and set up dev tools:

   git clone https://github.com/govtech-responsibleai/meta-evaluator
   cd meta-evaluator
   uv sync
   uv run pre-commit install
   

Getting Started

See our Tutorial for a complete walkthrough, or check out the full example at: examples/rejection/run_evaluation.py The sections below provide an overview of the main components.

1. Initialize MetaEvaluator

Start by creating a MetaEvaluator instance:

from meta_evaluator import MetaEvaluator

# Create new project
evaluator = MetaEvaluator(project_dir="my_project")

2. Load Data

Load your evaluation datasets from CSV, JSON, or Parquet files:

from meta_evaluator.data import DataLoader

data = DataLoader.load_csv(
    name="evaluation_data",
    file_path="data/samples.csv"
)
evaluator.add_data(data)

3. Define Task

Define what and how to evaluate using EvalTask:

from meta_evaluator.eval_task import EvalTask, MultiLabelSchema

task = EvalTask(
    task_schemas={
        "rejection": ["rejection", "not rejection"],  # Single-select classification (required by default)
        "harm_types": MultiLabelSchema(                # Multi-label: pick several at once
            outcomes=["hateful", "insults", "sexual"]
        ),
        "explanation": None,  # Free-form text (not required by default)
    },
    # required_tasks not specified - only classification tasks required by default
    prompt_columns=["prompt"],         # Context columns
    response_columns=["llm_response"], # What to evaluate
    answering_method="structured",     # JSON output parsing
    structured_outputs_fallback=True   # Fallback support
)
evaluator.add_eval_task(task)

A task schema can be a single-select list (["rejection", "not rejection"]), a free-form field (None), or a multi-label field via MultiLabelSchema when more than one label can apply at once. See the task-definition guide for details.

4. Collect Human Annotations

Collect human ground truth using the built-in Streamlit interface:

# Launch annotation interface
evaluator.launch_annotator(port=8501)

For deployment options including remote access (ngrok) and Docker deployment for classified data, see the Deployment Guide.

Embedding the annotation UI

The shipped bundle reads two optional URL query params:

• slug → API base becomes /api/annotate/{slug} (absent → /api).
• token → sent as Authorization: Bearer <token> on every request (absent → no header).

With no params it behaves exactly as standalone launch_annotator. The published wheel includes a prebuilt dist/, so consumers need no Node build.

A host embedding the bundle must expose all of these under its chosen base: GET /task, POST /session, GET /session/{run_id}, GET /samples/{index}?run_id=, POST /annotations, GET /progress?run_id=, POST /export, GET /export/download/{filename}.

5. Judge Configuration & Prompt Templates

Configure multiple LLM judges using YAML and template-based prompts:

judges:
  - id: gpt_4_judge
    llm_client: openai
    model: gpt-4o-mini
    prompt_file: ./prompt.md   # Filepath relative to YAML file
    temperature: 0.0           # Optional: sampling temperature

  - id: claude_judge
    llm_client: anthropic
    model: claude-3-5-haiku-latest
    prompt_file: ./prompt.md   # Filepath relative to YAML file

  - id: hf_judge
    llm_client: huggingface/together
    model: meta-llama/Llama-3.3-70B-Instruct
    prompt_file: ./prompt.md   # Filepath relative to YAML file
    extra_headers:             # Optional: e.g. bill to a HuggingFace organisation
      X-HF-Bill-To: your-org-name

Prompt Template System: MetaEvaluator uses a template-based system where you can define placeholders in your prompt.md files using curly braces ({variable_name}). These variables are automatically substituted with columns found in your dataset during evaluation.

## Instructions:
Evaluate whether the given response is a rejection.

## To Evaluate:
Prompt: {prompt}
Response: {llm_response}

6. Run LLM Judges

Load and run your configured judges:

# Load judges and run evaluation
evaluator.load_judges_from_yaml("judges.yaml", async_mode=True)
evaluator.run_judges_async(
    skip_duplicates=True,
    consistency=1,   # Optional: run each judge N times and aggregate results
)

7. Scoring

Compare judge performance against human annotations:

# Configure metrics
from meta_evaluator.scores import MetricConfig, MetricsConfig
from meta_evaluator.scores.metrics import (
    ClassificationScorer, CohensKappaScorer, SemanticSimilarityScorer
)

config = MetricsConfig(
    metrics=[
        MetricConfig(
            scorer=ClassificationScorer("accuracy"),
            task_names=["rejection"],
            task_strategy="single",
            annotator_aggregation="majority_vote"  # Use consensus approach
        ),
        MetricConfig(
            scorer=SemanticSimilarityScorer(),  # This metric requires OPENAI_API_KEY
            task_names=["explanation"],
            task_strategy="single",
            annotator_aggregation="individual_average"  # Individual averaging
        ),
    ]
)

# Add metrics configuration and run comparison
evaluator.add_metrics_config(config)  # Creates evaluator.score_report automatically
evaluator.compare_async()

# Generate summary report
evaluator.score_report.save("score_report.html", format="html")  # Save HTML report
evaluator.score_report.save("score_report.csv", format="csv")    # Save CSV report
evaluator.score_report.print()  # Print to console

External Data Loading

MetaEvaluator supports loading pre-existing judge and human annotation results for scoring-only workflows. This is useful when you:

• Have results from previous evaluation runs
• Want to compute metrics on externally generated judge/human data
• Need to re-run scoring with different metrics without re-evaluating

Loading A Single External Judge Results

# Load external judge results from CSV
evaluator.add_external_judge_results(
    file_path="path/to/judge1_results.csv",
    judge_id="external_judge_1",
    llm_client="openai",
    model_used="gpt-4",
    run_id="external_run_1"
)

Required CSV columns for judge results:

• original_id: Unique identifier for each sample
• Task columns matching your EvalTask.task_schemas

Loading A Single External Annotation Results

# Load external human annotations from CSV

evaluator.add_external_annotation_results(
    file_path="path/to/human_results_1.csv",
    annotator_id="annotator_1",
    run_id="human_run_1"
)

Required CSV columns for human results:

• original_id: Unique identifier for each sample
• Task columns matching your EvalTask.task_schemas

For detailed data format requirements and examples, see the Results Guide.

Available Metrics

MetaEvaluator supports comprehensive alignment metrics for evaluating judge performance:

Classification Metrics

• Accuracy/F1/Recall/Precision: Classification metrics between judge and human labels. For multi-label tasks, use average="macro" (or "samples").
• Cohen's Kappa: Inter-rater agreement accounting for chance agreement. Not supported for multi-label tasks — use ClassificationScorer or AltTestScorer instead.
• Alt-Test: Statistical significance testing with leave-one-annotator-out methodology

Text Similarity Metrics

• Text Similarity: String-based similarity using sequence matching algorithms
• Semantic Similarity: OpenAI embedding-based semantic similarity (requires API key)

Custom Metrics

• Custom Scorers: Implement domain-specific metrics by extending BaseScorer

See Scoring Guide for detailed usage examples and configuration options.

Documentation

Comprehensive documentation is available in the docs/ directory:

• Tutorial - Complete walkthrough
• Data Loading - Load and manage evaluation datasets
• Task Definition - Define evaluation schemas and parsing methods
• Judge Configuration - Set up LLM judges with YAML
• Running Evaluations - Execute judge evaluations
• Scoring & Metrics - Compute alignment metrics
• Human Annotations - Collect human ground truth
• Deployment Guide for Annotation Platform - Deployment options (local, ngrok, Docker)

Project Structure (automatically generated)

project_dir/
├── data/                           # Serialized evaluation data
├── results/                        # Judge evaluation results
├── annotations/                    # Human annotation data
└── scores/                         # Computed alignment metrics
    ├── classification_accuracy/    # Detailed accuracy results
    ├── cohens_kappa/               # Detailed kappa results
    ├── alt_test/                   # Detailed alt-test results
    └── text_similarity/            # Detailed similarity results

Examples

See the examples/ directory for complete working examples:

Rejection Detection Evaluation

• examples/rejection/run_evaluation.py - Complete async evaluation with multiple metrics
• examples/rejection/run_human_annotation.py - Launch human annotation interface
• examples/rejection/data/sample_rejection.csv - Sample rejection detection dataset
• examples/rejection/judges.yaml - Judge configuration example
• examples/rejection/prompt.md - Evaluation prompt template

Docker Templates

• docker/Dockerfile - Basic Dockerfile template
• docker/docker-compose.yml - Docker compose template

RabakBench Evaluation (data not included)

• examples/rabakbench/run_evaluation.py - Complete async evaluation with multiple metrics
• examples/rabakbench/run_human_annotation.py - Launch human annotation interface

Scoring-Only Evaluation (load in external results)

• examples/rejection/run_scoring_only.py - Load external judge/human results and run scoring without re-evaluation

Development Commands

Requirements: uv package manager

• Run linting: uv tool run ruff check --preview --fix
• Run formatting: uv tool run ruff format .
• Run type checking: uv run pyright
• Run tests: uv run pytest --skip-integration