Code Review Analyst

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README

<!-- mcp-name: io.github.j0hanz/code-lens -->

# Code Lens MCP Server

[![npm version](https://img.shields.io/npm/v/%40j0hanz%2Fcode-lens?style=flat-square&logo=npm)](https://www.npmjs.com/package/%40j0hanz%2Fcode-lens) [![License: MIT](https://img.shields.io/badge/license-MIT-blue?style=flat-square)](#contributing-and-license)

[![Install in VS Code](https://img.shields.io/badge/VS_Code-Install_Server-0098FF?style=flat-square&logo=visualstudiocode&logoColor=white)](https://insiders.vscode.dev/redirect/mcp/install?name=code-lens&config=%7B%22command%22%3A%22npx%22%2C%22args%22%3A%5B%22-y%22%2C%22%40j0hanz%2Fcode-lens%40latest%22%5D%7D) [![Install in VS Code Insiders](https://img.shields.io/badge/VS_Code_Insiders-Install_Server-24bfa5?style=flat-square&logo=visualstudiocode&logoColor=white)](https://insiders.vscode.dev/redirect/mcp/install?name=code-lens&config=%7B%22command%22%3A%22npx%22%2C%22args%22%3A%5B%22-y%22%2C%22%40j0hanz%2Fcode-lens%40latest%22%5D%7D&quality=insiders) [![Install in Visual Studio](https://img.shields.io/badge/Visual_Studio-Install_Server-C16FDE?logo=visualstudio&logoColor=white)](https://vs-open.link/mcp-install?%7B%22code-lens%22%3A%7B%22command%22%3A%22npx%22%2C%22args%22%3A%5B%22-y%22%2C%22%40j0hanz%2Fcode-lens%40latest%22%5D%7D%7D)

[![Add to LM Studio](https://files.lmstudio.ai/deeplink/mcp-install-light.svg)](https://lmstudio.ai/install-mcp?name=code-lens&config=eyJjb21tYW5kIjoibnB4IiwiYXJncyI6WyIteSIsIkBqMGhhbnovY29kZS1sZW5zQGxhdGVzdCJdfQ==) [![Install in Cursor](https://cursor.com/deeplink/mcp-install-dark.svg)](https://cursor.com/en/install-mcp?name=code-lens&config=eyJjb21tYW5kIjoibnB4IiwiYXJncyI6WyIteSIsIkBqMGhhbnovY29kZS1sZW5zQGxhdGVzdCJdfQ==) [![Install in Goose](https://block.github.io/goose/img/extension-install-dark.svg)](https://block.github.io/goose/extension?cmd=npx&arg=-y&arg=%40j0hanz%2Fcode-lens%40latest&id=%40j0hanz%2Fcode-lens&name=code-lens&description=Gemini-powered%20MCP%20server%20for%20code%20analysis.)

Gemini-powered MCP server for automated code review, analysis, and documentation.

## Overview

Code Lens is a [Model Context Protocol](https://modelcontextprotocol.io/) server that uses Google Gemini to analyze diffs, review pull requests, detect code smells, generate documentation, and verify logic. It exposes 13 tools, 7 resources, and 5 prompts over stdio transport.

## Key Features

- **PR review pipeline** — generate diffs, assess impact, detect breaking API changes, and produce review summaries with merge recommendations
- **File analysis** — load any source file for refactoring suggestions, code smell detection, documentation generation, and natural-language Q&A
- **Logic verification** — verify algorithms using Gemini's code execution sandbox
- **Structured outputs** — all tools return validated JSON via Zod v4 output schemas
- **Web search** — Google Search with Grounding for up-to-date information retrieval
- **Task lifecycle support** — every tool except `load_file` can run via MCP tasks with polling, cancellation, and progress updates

## Requirements

- Node.js >= 24
- A [Gemini API key](https://aistudio.google.com/apikey) (`GEMINI_API_KEY` or `GOOGLE_API_KEY`)

## Quick Start

```json
{
  "mcpServers": {
    "code-lens": {
      "command": "npx",
      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],
      "env": {
        "GEMINI_API_KEY": "your-api-key"
      }
    }
  }
}
```

### Docker

```bash
docker run -i --rm -e GEMINI_API_KEY="your-api-key" ghcr.io/j0hanz/code-lens
```

Or with Docker Compose:

```bash
GEMINI_API_KEY=your-api-key docker compose up
```

## Client Configuration

<details>
<summary><b>Install in VS Code</b></summary>

[![Install in VS Code](https://img.shields.io/badge/VS_Code-Install_Server-0098FF?style=flat-square&logo=visualstudiocode&logoColor=white)](https://insiders.vscode.dev/redirect/mcp/install?name=code-lens&config=%7B%22command%22%3A%22npx%22%2C%22args%22%3A%5B%22-y%22%2C%22%40j0hanz%2Fcode-lens%40latest%22%5D%7D)

Add to `.vscode/mcp.json`:

```json
{
  "servers": {
    "code-lens": {
      "command": "npx",
      "args": ["-y", "@j0hanz/code-lens-mcp@latest"],
      "env": {
        "GEMINI_API_KEY": "your-api-key"
      }
    }
  }
}
```

Or install via CLI:

```sh
code --add-mcp '{"name":"code-lens","command":"npx","args":["-y","@j0hanz/code-lens-mcp@latest"]}'
```

For more info, see [VS Code MCP docs](https://code.visualstudio.com/docs/copilot/chat/mcp-servers).

</details>

<details>
<summary><b>Install in VS Code Insiders</b></summary>

[![Install in VS Code Insiders](https://img.shields.io/badge/VS_Code_Insiders-Install_Server-24bfa5?style=flat-square&logo=visualstudiocode&logoColor=white)](https://insiders.vscode.dev/redirect/mcp/install?name=code-lens&config=%7B%22command%22%3A%22npx%22%2C%22args%22%3A%5B%22-y%22%2C%22%40j0hanz%2Fcode-lens%40latest%22%5D%7D&quality=insiders)

Add to `.vscode/mcp.json`:

```json
{
  "servers": {
    "code-lens": {
      "command": "npx",
      "args": ["-y", "@j0