Vitest MCP Server

AI-optimized Vitest interface with structured output, visual debugging, and intelligent coverage analysis.

Problem & Solution

The Problem

When AI assistants help with testing, they typically run raw Vitest commands that produce:

❌ Verbose terminal output that's hard for AI to parse
❌ Missing failure context - no code snippets or visual indicators
❌ Accidental full test runs when no target is specified
❌ Basic coverage metrics without actionable insights

The Solution

This MCP server provides AI-optimized testing tools that deliver:

✅ Structured JSON output designed for AI consumption
✅ Visual debugging context with code snippets and failure markers
✅ Intelligent targeting prevents accidental full test suite runs
✅ Coverage gap analysis with line-by-line insights and recommendations

Features

🎯 Smart Test Execution - Run specific files/folders with structured output
📊 Coverage Analysis - Line-by-line gap analysis with actionable insights
📁 Test Discovery - Find and organize test files across your project
🔗 Claude Code Hooks - Automatic interception of Vitest commands
🛡️ Safety Guards - Prevents accidental full project test runs

Quick Start

1. Add to Claude Desktop

Add this to your Claude Desktop configuration:

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

{
  "mcpServers": {
    "vitest": {
      "command": "npx",
      "args": ["-y", "@djankies/vitest-mcp"]
    }
  }
}

2. Restart Claude Desktop

3. Start Using

Ask Claude to:

"Run tests in the components folder"
"Check coverage for the auth module"
"List all test files"

Requirements

Minimum Versions

Node.js: 18+
Vitest: 0.34.0+ (3.0.0+ recommended)
Coverage Provider: @vitest/coverage-v8 (for coverage analysis)

npm install --save-dev vitest@latest @vitest/coverage-v8@latest

Project Setup

Ensure your vitest.config.ts includes:

export default defineConfig({
  test: {
    coverage: {
      provider: 'v8',
      reporter: ['text', 'json', 'html']
    }
  }
})

Tools

`list_tests`

List test files in your project.

list_tests({ directory: "./src" })

`run_tests`

Execute tests with AI-optimized output.

run_tests({ 
  target: "./src/components", 
  format: "detailed" // or "summary"
})

`analyze_coverage`

Analyze test coverage with gap insights.

analyze_coverage({
  target: "./src/api",
  threshold: 80,
  format: "detailed"
})

Claude Code Hook Integration (Recommended)

Automatically intercept Vitest commands and suggest MCP tools.

Copy hook script

curl -o .claude/vitest-hook.sh https://raw.githubusercontent.com/djankies/vitest-mcp/main/hooks/vitest-hook.sh
chmod +x .claude/vitest-hook.sh

Update .claude/settings.local.json

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": ".claude/vitest-hook.sh"
          }
        ]
      }
    ]
  }
}

Configuration Options

MCP Server Options

{
  "mcpServers": {
    "vitest": {
      "command": "npx",
      "args": [
        "-y", "@djankies/vitest-mcp",
        "--format", "detailed",
        "--timeout", "60000"
      ]
    }
  }
}

Available CLI Options

--format <summary|detailed> - Default output format
--timeout <ms> - Test timeout (default: 30000)
--verbose - Debug information

Troubleshooting

Version Issues

# Check compatibility
npx -y @djankies/vitest-mcp --version-check

Common Issues

"Vitest not found"

npm install --save-dev vitest@latest

"Coverage provider not found"

npm install --save-dev @vitest/coverage-v8@latest

Hook not working

# Test hook directly
./.claude/vitest-hook.sh vitest run src/
# Bypass hook
npx vitest run src/ --bypass-hook

License

MIT

Install Server

HTTP connection URL

security – no known vulnerabilities

license - not found

quality - confirmed to work

How are these scores calculated?

Tools

AI-optimized Vitest interface that provides structured test output, visual debugging context, and intelligent coverage analysis for more effective AI assistance with testing.

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