Devserver

DevServer MCP monitors development server logs in real-time, categorizes errors by type and severity, and pushes immediate, structured error notifications to Claude Code via Server-Sent Events. It helps you spot, classify, and correlate issues as you develop, so you can act quickly without sifting through logs.

How to use

You connect Claude Code to the DevServer MCP using the SSE transport. Once connected, you receive real-time, categorized error alerts. Each error carries a type, a severity (critical, warning, info), and a file location to help you pinpoint the issue. Multiple Claude Code instances can stay connected at the same time, so your whole team gets instant notifications. You’ll see errors linked to recent file changes and can ask questions like “How do I fix this?” while browsing the structured data.

Key capabilities you’ll use regularly:

• Instant notifications when errors occur
• Intelligent parsing for TypeScript, Svelte, and Vite patterns
• Error correlation with recent file changes
• Clear severity classification (critical, warning, info)
• Support for multiple Claude Code clients
• Structured error data delivered instead of raw logs

How to install

Prerequisites you need before starting: a Node.js runtime and a package manager that matches your project workflow.

# Install dependencies and build the MCP server
pnpm install
pnpm build

# Start monitoring with SSE server (default port 9338)
node dist/server.js --monitor pnpm run dev

# Connect Claude Code to the MCP server
claude mcp add --transport sse devserver_mcp http://127.0.0.1:9338/sse

Configuration and ports

The server exposes a streaming endpoint over SSE. You can run separate instances for different projects and connect each one to Claude Code using distinct names and ports for isolation.

You can run with the default port or specify a custom port per project.

# Default port 9338
node dist/server.js --monitor pnpm run dev
claude mcp add --transport sse devserver_mcp http://127.0.0.1:9338/sse

# Custom ports per project
node dist/server.js --port 9339 --monitor pnpm run dev
node dist/server.js --port 9340 --monitor npm run dev:api

claude mcp add --transport sse frontend_devserver http://127.0.0.1:9339/sse
claude mcp add --transport sse backend_devserver http://127.0.0.1:9340/sse

MCP tools and endpoints

The MCP exposes several helper tools to inspect status and history of errors.

Tools you can use:

• get_dev_server_status — Current server health and error counts
• get_error_summary — Errors grouped by type and severity
• get_error_history — Chronological error list with filtering
• get_file_errors — Errors for a specific file
• suggest_monitoring_setup — Project-specific setup recommendations

Error categories

Errors are categorized by common developer pain points so you can triage quickly. Categories include TypeScript compilation issues, Svelte component warnings, Vite build failures, network/API errors, runtime JavaScript errors, and accessibility issues.

Architecture

The system streams errors in real time using Server-Sent Events. It runs in a monitor mode that parses logs, classifies errors, and broadcasts them to connected Claude Code clients. An HTTP server serves the /sse endpoint for all clients, and recent errors are buffered so new clients receive context immediately.

Real-time updates reach Claude Code within 1–2 seconds of an issue occurring.

Configuration example

{
  "processPatterns": ["pnpm run dev", "npm run dev"],
  "historyLimit": 1000,
  "correlationWindow": 5000,
  "watchPaths": ["src", "lib"],
  "excludePaths": ["node_modules", ".git"],
  "patterns": [
    {
      "name": "custom-error",
      "pattern": "CUSTOM: (.+)",
      "category": "runtime",
      "severity": "critical"
    }
  ]
}

Troubleshooting

If you don’t receive real-time notifications, verify MCP connections and port usage, then reconnect to the correct SSE endpoint. If a port is already in use, adjust the port for the target project and re-link Claude Code.

Common checks include verifying that the monitoring server is running and that Claude Code points to the correct /sse URL for the intended port.

Available tools

get_dev_server_status

Retrieves the current health of the MCP server and counts of active errors.

get_error_summary

Provides an aggregated view of errors grouped by type and severity.

get_error_history

Returns a chronological list of errors with optional filtering.

get_file_errors

Fetches all errors associated with a specific source file.

suggest_monitoring_setup

Offers project-specific recommendations for configuring monitoring.