mcp-llm-eval 0.1.0

MCP server that packages LLM evaluation gates as reusable CI/CD primitives

mcp-llm-eval

A local Model Context Protocol (MCP) server that packages LLM evaluation gates as reusable CI/CD primitives. Run datasets against multiple models, score responses with an LLM-as-judge, and enforce quality thresholds — all through MCP tools that AI agents can call.

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Why?

There's no unit test for LLM quality. Teams ship prompt changes, swap models, or update system prompts with no automated way to verify that output quality didn't regress. Manual spot-checking doesn't scale, and existing eval frameworks are heavy, opinionated, and hard to wire into CI/CD.

mcp-llm-eval gives AI agents structured access to a lightweight eval pipeline. Instead of building custom scripts for every project, you define a dataset, point the agent at it, and get scored results with pass/fail gates — the same workflow whether you're testing locally or gating a deployment.

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Features

Tool	Description
run_evaluation	Load a dataset, query models via streaming, score with LLM-as-judge, return per-question scores and aggregate summary
check_thresholds	Validate evaluation results against quality gates (faithfulness, relevance, TTFT, cost)
list_evaluations	List past evaluation runs with metadata (timestamp, models, cost, pass/fail)
get_evaluation	Retrieve full details of a specific run (per-question scores, responses, judge reasoning)

What it measures

• Faithfulness (0-1) — Is the response grounded in the provided context?
• Relevance (0-1) — Does the response actually answer the question?
• Time to First Token — Streaming latency in milliseconds
• Cost per Query — Estimated cost based on token usage and provider pricing

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Quick Start

1. Install

pip install mcp-llm-eval

Then install the provider SDKs you need (they are not bundled):

# Pick what you use
pip install anthropic    # for Claude models
pip install openai       # for GPT models + judge
pip install google-genai # for Gemini models

2. Configure Claude Desktop

Add this to your Claude Desktop MCP configuration file:

OS	Path
macOS	~/Library/Application Support/Claude/claude_desktop_config.json
Windows	%APPDATA%\Claude\claude_desktop_config.json

Recommended — with uvx (no install required):

{
  "mcpServers": {
    "llm-eval": {
      "command": "uvx",
      "args": ["mcp-llm-eval"],
      "env": {
        "ANTHROPIC_API_KEY": "sk-ant-...",
        "OPENAI_API_KEY": "sk-...",
        "GOOGLE_API_KEY": "AIza..."
      }
    }
  }
}

Note: Only include API keys for the providers you plan to evaluate. For example, if you only use Anthropic and OpenAI (for the judge), omit GOOGLE_API_KEY.

Note: Claude Desktop may not inherit your terminal's $PATH. If the server fails to connect, use the absolute path to uvx (find it with which uvx):

{
  "mcpServers": {
    "llm-eval": {
      "command": "/full/path/to/uvx",
      "args": ["mcp-llm-eval"],
      "env": {
        "ANTHROPIC_API_KEY": "sk-ant-...",
        "OPENAI_API_KEY": "sk-..."
      }
    }
  }
}

Alternative — installed via pip:

{
  "mcpServers": {
    "llm-eval": {
      "command": "mcp-llm-eval",
      "env": {
        "ANTHROPIC_API_KEY": "sk-ant-...",
        "OPENAI_API_KEY": "sk-...",
        "GOOGLE_API_KEY": "AIza..."
      }
    }
  }
}

Alternative — from source (virtualenv):

{
  "mcpServers": {
    "llm-eval": {
      "command": "/absolute/path/to/mcp-llm-eval/.venv/bin/python",
      "args": ["-m", "mcp_llm_eval.server"],
      "env": {
        "ANTHROPIC_API_KEY": "sk-ant-...",
        "OPENAI_API_KEY": "sk-...",
        "GOOGLE_API_KEY": "AIza..."
      }
    }
  }
}

3. Restart Claude Desktop

Fully quit (Cmd+Q on macOS) and reopen. Look for the tools icon to confirm the server is connected.

4. Ask a question

"Run the eval dataset at /path/to/dataset.json against Claude Sonnet and GPT-4o, then check if faithfulness is above 0.8."

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Example interaction

Claude autonomously chains the tools — running the evaluation, then checking thresholds:

Running evaluation...
- Dataset: 10 questions (4 factual, 3 reasoning, 3 summarization)
- Models: claude-sonnet-4-6, gpt-4o-mini
- Judge: gpt-4o-mini

Results:
  claude-sonnet-4-6: avg faithfulness=0.92, relevance=0.88, TTFT=340ms, cost=$0.0045/q
  gpt-4o-mini:           avg faithfulness=0.85, relevance=0.82, TTFT=180ms, cost=$0.0003/q

Threshold check:
  avg_faithfulness >= 0.80: PASS (actual: 0.885)
  avg_relevance >= 0.75:    PASS (actual: 0.850)
  p95_ttft_ms <= 500:       PASS (actual: 420ms)
  max_cost_per_query <= 0.01: PASS (actual: $0.0045)

Overall: PASS

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Configuration

Create an .eval-gate.yml in your project root for repeatable threshold configs:

thresholds:
  avg_faithfulness: 0.80
  avg_relevance: 0.75
  p95_ttft_ms: 500
  max_cost_per_query: 0.01

models:
  - provider: anthropic
    model: claude-sonnet-4-6
    input_cost_per_mtok: 3.0
    output_cost_per_mtok: 15.0
  - provider: openai
    model: gpt-4o-mini
    input_cost_per_mtok: 0.15
    output_cost_per_mtok: 0.60

judge:
  provider: openai
  model: gpt-4o-mini
  temperature: 0

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Dataset schema

The evaluation dataset is a JSON array of entries:

[
  {
    "id": "unique-id",
    "category": "factual",
    "context": "The system prompt / context provided to the model",
    "question": "The question asked",
    "expected_response": "Reference answer for the judge to compare against",
    "tags": ["optional", "tags"]
  }
]

Required fields: id, category, context, question, expected_response. The tags field is optional.

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Usage modes

MCP agent (v0.1.0)

Connect to Claude Desktop or any MCP-compatible agent. The agent calls tools directly — run evals, check thresholds, browse past runs.

CLI in GitHub Actions (coming in v0.2.0)

# .github/workflows/eval-gate.yml (coming soon)
- name: Run LLM eval gate
  run: mcp-llm-eval check --config .eval-gate.yml --dataset eval/dataset.json

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Troubleshooting

Server not appearing in Claude Desktop

1. Ensure Claude Desktop is fully restarted (quit with Cmd+Q, not just close the window).
2. Check your config JSON is valid — a trailing comma or typo will silently break it.
3. Use absolute paths if uvx or mcp-llm-eval aren't found.

"Provider SDK not installed" errors

Provider SDKs are optional. Install the ones you need:

pip install anthropic openai google-genai

"Dataset file not found" errors

Use the full absolute path to your dataset file, not a relative path.

Judge scoring fails

The default judge uses OpenAI's gpt-4o-mini. Make sure the openai package is installed and OPENAI_API_KEY is set in your environment.

This is Claude Desktop only

MCP servers work with the Claude Desktop app, not claude.ai in your browser.

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Development

# Clone and set up
git clone https://github.com/berkayildi/mcp-llm-eval.git
cd mcp-llm-eval
make setup

# Run tests
make test

# Build distribution
make build

# Run the server locally (stdio)
make start

# Clean everything
make clean

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License

MIT © Berkay Yildirim