Web UX Evaluator MCP server for AI agents

The operative.sh web-eval-agent MCP server provides an automated solution for debugging web applications directly in your code editor, allowing coding agents to autonomously execute and test web apps so you can focus on more important tasks.

Getting Started

Quick Setup with One-Click Integration

Get your API key (free) - when you create your API key, you'll see:
- "Add to Cursor" button with a deeplink for instant Cursor installation
- Prefilled Claude Code command with your API key automatically included

Automatic Setup (macOS/Linux)

Prerequisites (typically not needed):

brew:

/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:

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

Restart your IDE to apply the changes

Use the web-eval-agent by sending a prompt in chat mode:

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

Manual Installation

Get your API key

Install uv:

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

Source environment variables after installing UV:

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, replacing <YOUR_KEY> 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

Usage

MCP Tool Reference

The MCP server provides two main tools:

web_eval_agent: Automated UX evaluator that drives the browser, captures screenshots, console & network logs, and returns a rich UX report.
setup_browser_state: Opens an interactive (non-headless) browser so you can sign in once; the saved cookies/local-storage are reused by subsequent web_eval_agent runs.

Key Arguments

web_eval_agent

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

setup_browser_state

url (optional) – Page to open first (handy to land directly on a login screen)

Example Command

You can trigger these tools straight from your IDE chat, for example:

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

Updating the MCP Server

To update the MCP server:

uv cache clean

Then refresh your MCP server.

Troubleshooting

If updates aren't being received in code editors, update or reinstall for the latest version: Run uv cache clean for latest
For static apps without changes not screencasting, run uv clean + restart to get the fix

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