Web UX Evaluator MCP server for AI agents

The MCP Server by operative.sh provides autonomous browser-based testing and debugging for web applications, allowing AI agents to execute and evaluate web apps directly from your code editor.

Quick Installation

macOS/Linux Automatic Installation

Prerequisites (usually already installed):
- Homebrew: /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
- npm: brew install npm
- jq: brew install jq

Run the installer script (after getting a free API key):

curl -LSf https://operative.sh/install.sh -o install.sh && bash install.sh && rm install.sh

Restart your code editor (Cursor/Cline/Windsurf)

Test the installation by sending a prompt in chat mode:

Test my app on http://localhost:3000. Use web-eval-agent.

Manual Installation

Get your API key at operative.sh/mcp

Install uv:

curl -LsSf https://astral.sh/uv/install.sh | sh

Source environment variables:

# Mac
source ~/.zshrc

# Linux
source ~/.bashrc

Install Playwright:

npm install -g chromium playwright && uvx --with playwright playwright install --with-deps

Add the following JSON to your code editor configuration with your API key:

"web-eval-agent": {
  "command": "uvx",
  "args": [
    "--refresh-package",
    "webEvalAgent",
    "--from",
    "git+https://github.com/Operative-Sh/web-eval-agent.git",
    "webEvalAgent"
  ],
  "env": {
    "OPERATIVE_API_KEY": "<YOUR_KEY>"
  }
}

Restart your code editor

Using the MCP Server

Available Tools

The MCP Server provides two main tools:

web_eval_agent: Automated UX evaluator that drives the browser, captures screenshots, console logs, network logs, and returns a detailed UX report.
setup_browser_state: Opens an interactive browser for you to sign in once; the saved cookies and local storage will be reused by subsequent web_eval_agent runs.

Key Arguments

For the web_eval_agent tool:

url (required): Address of the running app (e.g., http://localhost:3000)
task (required): Natural-language description of what to test (e.g., "run through the signup flow and note any UX issues")
headless_browser (optional, default false): Set to true to hide the browser window

For the setup_browser_state tool:

url (optional): Page to open first (useful for landing directly on a login screen)

Example Usage

To test your web application, simply use a prompt like:

Evaluate my app at http://localhost:3000 – run web_eval_agent with the task "Try the full signup flow and report UX issues".

Troubleshooting

If you encounter issues:

Run uv cache clean to ensure you have the latest updates
Restart your code editor after installation or updates
For Windows installation issues, refer to the manual installation steps through your code editor terminal

Updating

To update to the latest version:

Run uv cache clean
Refresh the MCP server by restarting your code editor

How to install this MCP server

For Claude Code

To add this MCP server to Claude Code, run this command in your terminal:

claude mcp add-json "web-eval-agent" '{"command":"uvx","args":["--refresh-package","webEvalAgent","--from","git+https://github.com/Operative-Sh/web-eval-agent.git","webEvalAgent"],"env":{"OPERATIVE_API_KEY":"<YOUR_KEY>"}}'

See the official Claude Code MCP documentation for more details.

For Cursor

There are two ways to add an MCP server to Cursor. The most common way is to add the server globally in the ~/.cursor/mcp.json file so that it is available in all of your projects.

If you only need the server in a single project, you can add it to the project instead by creating or adding it to the .cursor/mcp.json file.

Adding an MCP server to Cursor globally

To add a global MCP server go to Cursor Settings > Tools & Integrations and click "New MCP Server".

When you click that button the ~/.cursor/mcp.json file will be opened and you can add your server like this:

{
    "mcpServers": {
        "web-eval-agent": {
            "command": "uvx",
            "args": [
                "--refresh-package",
                "webEvalAgent",
                "--from",
                "git+https://github.com/Operative-Sh/web-eval-agent.git",
                "webEvalAgent"
            ],
            "env": {
                "OPERATIVE_API_KEY": "<YOUR_KEY>"
            }
        }
    }
}

Adding an MCP server to a project

To add an MCP server to a project you can create a new .cursor/mcp.json file or add it to the existing one. This will look exactly the same as the global MCP server example above.

How to use the MCP server

Once the server is installed, you might need to head back to Settings > MCP and click the refresh button.

The Cursor agent will then be able to see the available tools the added MCP server has available and will call them when it needs to.

You can also explicitly ask the agent to use the tool by mentioning the tool name and describing what the function does.

For Claude Desktop

To add this MCP server to Claude Desktop:

1. Find your configuration file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%\Claude\claude_desktop_config.json
Linux: ~/.config/Claude/claude_desktop_config.json

2. Add this to your configuration file:

{
    "mcpServers": {
        "web-eval-agent": {
            "command": "uvx",
            "args": [
                "--refresh-package",
                "webEvalAgent",
                "--from",
                "git+https://github.com/Operative-Sh/web-eval-agent.git",
                "webEvalAgent"
            ],
            "env": {
                "OPERATIVE_API_KEY": "<YOUR_KEY>"
            }
        }
    }
}

3. Restart Claude Desktop for the changes to take effect