Setup Guide

Add Assay to Your Editor

Verify code directly inside Claude Code, Cursor, or Windsurf. No terminal needed — the MCP server runs in the background and gives your AI assistant access to Assay's verification tools.

3 minutesIDE integration

What is an MCP server?

MCP (Model Context Protocol) is the standard way to give AI coding assistants new abilities. Think of it like installing a plugin for your editor's AI.

When you add the Assay MCP server, your AI assistant gets 4 new tools it can use while helping you code:

verify-code

Paste code and get a verification report

verify-file

Point at any file in your project to verify it

generate-code

Generate verified code from a description

health-check

Confirm the connection to Assay is working

Before you start

Node.js 20 or newer installed. Check with node --version
One of these editors: Claude Code, Cursor, or Windsurf

Create your Assay account

Head to the signup page and create a free account. No credit card required.

Create Free Account

Already have an account? Log in instead.

Copy your API key

After signing in, go to your API Keys page. Click Generate New Key and copy the key that starts with lk_live_.

Save your key somewhere safe. You will not be able to see it again after leaving the page. You will paste it into your editor's config in the next step.

Add the MCP config to your editor

Choose your editor, then follow the instructions to add Assay.

Open Claude Code in your terminal
Type /mcp to see your MCP settings
Or edit the config file directly (path shown below)
Paste the configuration and save
Restart Claude Code

Config file location: ~/.claude/claude_desktop_config.json

json

{
  "mcpServers": {
    "assay": {
      "command": "npx",
      "args": ["-y", "assay-mcp"],
      "env": {
        "ASSAY_API_KEY": "lk_live_your_key_here"
      }
    }
  }
}

Replace the API key

Find lk_live_your_key_here in the config above and replace it with the real key you copied in Step 2. Everything else stays the same.

Try it out

After restarting your editor, the AI assistant now has access to Assay's tools. Try asking it to verify some code:

>“Can you verify this file for bugs?”

>“Use Assay to check src/auth/login.ts”

>“Generate a verified rate limiter in TypeScript”

>“Run a health check on the Assay connection”

The assistant will call the Assay MCP tools automatically and show you the results inline. You will see claims extracted from your code, verification verdicts for each one, and specific fix suggestions for anything that fails.

You are all set

Assay is now running inside your editor. Every time you ask your AI assistant to verify code, it uses the same pipeline that caught bugs in projects with 50K+ GitHub stars.

Troubleshooting

The tools do not appear in my editor

Make sure you restarted the editor after adding the config. In Claude Code, type /mcp to check if Assay is listed. In Cursor, check Settings > MCP to see connected servers.

I get 'ASSAY_API_KEY environment variable is required'

Your API key is missing or not set correctly in the config. Double-check that you replaced lk_live_your_key_here with your real key and that there are no extra spaces.

I get '401 Unauthorized' errors

Your API key may be invalid or expired. Go to your dashboard, generate a new key, and update the config.

The server takes a long time to start

The first launch downloads the package from npm. This can take 10-20 seconds on a slow connection. Subsequent launches are instant.

Prefer the command line?

Run assessments from your terminal with the Assay CLI.

CLI Setup Guide