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Spotlight
by Sentry

MCP Server

The Spotlight MCP (Model Context Protocol) server enables AI coding assistants like Cursor, Claude, and others to access your application’s runtime data for debugging and development assistance.

What is MCP?

Model Context Protocol is an open standard that allows AI assistants to securely access external data sources and tools. Spotlight’s MCP server provides tools that let your AI assistant:

  • Search through application errors with full stack traces
  • Query logs to understand application behavior
  • Inspect performance traces and identify bottlenecks
  • Get detailed timing information for distributed traces

Why Use Spotlight with MCP?

When debugging with an AI coding assistant, it can now access actual runtime data from your application instead of just analyzing static code. This means:

  • Context-aware debugging: Your AI assistant sees the actual errors, not just the code
  • Real-time insights: Access to live traces and logs during development
  • Faster issue resolution: AI can analyze stack traces and suggest fixes based on real data
  • Better performance analysis: AI can identify slow operations from trace data

Quick Start

1. Install Spotlight MCP Server

We recommend using npx to always get the latest version:

For Claude Desktop:

Terminal window
claude mcp add sentry-spotlight -- npx -y --prefer-online @spotlightjs/spotlight@latest mcp

For Cursor:

Click the button below or add manually:

Add spotlight MCP server to Cursor

2. Manual Configuration (Alternative)

If you prefer to configure manually, add Spotlight to your MCP client configuration:

Add to your Cursor MCP settings (.cursor/mcp.json or Cursor settings UI):

{
  "mcpServers": {
    "spotlight": {
      "command": "npx",
      "args": ["-y", "--prefer-online", "@spotlightjs/spotlight@latest", "mcp"]
    }
  }
}

3. Run Your Application

Make sure your application is running and sending telemetry to Spotlight.

Option 1 - Use Spotlight CLI:

Terminal window
spotlight run npm run dev

Option 2 - Set environment variable:

Terminal window
export SENTRY_SPOTLIGHT=1
npm run dev

4. Use in Your AI Assistant

Now your AI assistant has access to Spotlight tools! Try asking:

  • “Are there any errors in my application?”
  • “Show me recent errors in the auth.js file”
  • “What traces do we have from the last 5 minutes?”
  • “Analyze the performance of trace ID abc123”
  • “Show me logs related to database operations”

Available Tools

The MCP server provides four powerful tools:

search_errors

Search for application errors with stack traces and context.

Perfect for:

  • Finding runtime errors and exceptions
  • Investigating crashes and failures
  • Analyzing error patterns

See detailed documentation →

search_logs

Query application logs to understand behavior and flow.

Perfect for:

  • Understanding application execution flow
  • Finding debug information
  • Analyzing timing and performance from logs

See detailed documentation →

search_traces

List recent performance traces with summary information.

Perfect for:

  • Getting an overview of recent requests
  • Identifying slow operations
  • Finding traces with errors

See detailed documentation →

get_traces

Get detailed span tree and timing for a specific trace.

Perfect for:

  • Deep-diving into performance issues
  • Analyzing distributed traces
  • Understanding request flow and timing

See detailed documentation →

View complete tools reference →

Configuration

Custom Port

If you need to run Spotlight on a different port:

Terminal window
spotlight mcp -p 3000

Update your MCP client configuration to match:

{
  "mcpServers": {
    "spotlight": {
      "command": "spotlight",
      "args": ["mcp", "-p", "3000"]
    }
  }
}

Debug Mode

Enable debug logging to troubleshoot MCP connection issues:

Terminal window
spotlight mcp -d

How It Works

The MCP integration connects your AI assistant to live application data:

  1. Your Application sends telemetry (errors, logs, traces) to the Spotlight sidecar via Sentry SDK
  2. Spotlight Sidecar stores events in memory and provides them via MCP tools
  3. MCP Client (Cursor, Claude, etc.) connects to Spotlight via stdio
  4. AI Assistant uses MCP tools to query events and help with debugging
Your App → Sentry SDK → Spotlight Sidecar ← MCP Client ← AI Assistant
                              ↓
                        [Errors, Logs, Traces]

Requirements

Sentry SDK

Your application must have a Sentry SDK configured to send events to Spotlight:

import * as Sentry from '@sentry/node';


Sentry.init({
  dsn: 'your-dsn', // Optional for local dev
  // Spotlight is auto-enabled if SENTRY_SPOTLIGHT env var is set
});

MCP Client

You need an MCP-compatible client such as:

Example Workflow

Here’s a typical debugging session with Spotlight MCP:

  1. Start Spotlight MCP Server

    Terminal window
    spotlight mcp

  2. Run Your Application

    Terminal window
    spotlight run npm run dev

  3. Trigger an Error in your application (e.g., click a button, make a request)

  4. Ask Your AI Assistant

    You: "Are there any errors in my app?"
    

    AI: I'll check Spotlight for errors...
    [Calls search_errors]
    

    AI: "Yes, there's a TypeError in auth.js at line 42:
         Cannot read property 'id' of undefined
    

         The error occurs in the getUserData function.
         Would you like me to analyze the code?"

  5. Deep Dive with Follow-ups

    You: "Show me the full trace for this request"
    

    AI: [Calls search_traces and get_traces]
    

    AI: "Here's the trace:
         - Total duration: 245ms
         - Database query: 45ms
         - External API call: 180ms (this is slow!)
         - Error occurred during user data processing
    

         The external API call is taking most of the time.
         The error happens because the API returned null."

Troubleshooting

MCP Server Not Starting

Check that the port isn’t already in use:

Terminal window
# Use a different port
spotlight mcp -p 3000


# Enable debug logging
spotlight mcp -d

AI Assistant Not Seeing Tools

  1. Verify MCP server is running
  2. Check your MCP client configuration is correct
  3. Restart your MCP client after configuration changes
  4. Check client logs for connection errors

No Events Available

  1. Ensure your application is running
  2. Verify Sentry SDK is configured
  3. Trigger some activity (errors, requests) in your app
  4. Check that SENTRY_SPOTLIGHT environment variable is set or SDK has spotlight enabled

Next Steps