DevServer MCP

An MCP server that monitors development server logs in real-time, categorizes errors by type and severity, and provides Claude Code with immediate error notifications via Server-Sent Events (SSE).

DevServer MCP:

Real-time notifications: Instant error alerts via SSE transport
Intelligent parsing: Recognizes TypeScript, Svelte, Vite error patterns
Error correlation: Links errors to recent file changes
Severity classification: Critical vs warning vs info
Multiple client support: Connect multiple Claude Code instances simultaneously
AI integration: Claude Code receives structured error data instead of raw logs

Quick Start

# Install and build pnpm install && pnpm build # Start monitoring with SSE server (uses default port 9338) node dist/server.js --monitor pnpm run dev # Connect Claude Code (port stays consistent across restarts) claude mcp add --transport sse devserver-mcp http://127.0.0.1:9338/sse

Now Claude Code receives immediate notifications when errors occur!

Core Workflow

Traditional debugging:

Notice something broken → 2. Scroll through terminal → 3. Find relevant error → 4. Google it

With DevServer MCP:

Error occurs → 2. Instant notification in Claude Code → 3. Get categorized errors with file locations → 4. Ask "How do I fix this?"

MCP Tools

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

Port Configuration

Default Port (9338):

# Start with default port node dist/server.js --monitor pnpm run dev # Connect Claude Code claude mcp add --transport sse devserver-mcp http://127.0.0.1:9338/sse

Custom Port Per Project:

# Frontend project on port 9339 node dist/server.js --port 9339 --monitor pnpm run dev # Backend project on port 9340 node dist/server.js --port 9340 --monitor npm run dev:api # Connect to specific projects 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

Benefits:

✅ Consistent ports - same port every restart, no need to re-add MCP server
✅ Per-project ports - run multiple projects simultaneously
✅ Conflict detection - helpful error messages if port is already in use

Architecture

SSE-Based Real-Time System:

Monitor mode (--monitor): Spawns dev server, parses logs, broadcasts errors via SSE
HTTP server: Serves /sse endpoint for Claude Code connections on specified port
Error buffering: Maintains recent error history for newly connected clients
Multi-client support: Multiple Claude Code instances can connect simultaneously

Real-time error streaming means Claude Code gets notified within 1-2 seconds of any dev server issue.

Error Categories

Built-in patterns for:

TypeScript compilation errors
Svelte component warnings
Vite build failures
Network/API errors
Runtime JavaScript errors
Accessibility issues

Configuration

Create devserver-mcp.config.json:

{ "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" } ] }

Development

pnpm install # Install deps pnpm build # Build project pnpm dev # Watch mode pnpm test # Run tests pnpm typecheck # Type checking

Troubleshooting

Connection Failed

# Check if monitoring server is running ps aux | grep "node.*server.js" # Restart monitoring server (default port 9338) node dist/server.js --monitor pnpm run dev # Verify connection claude mcp add --transport sse devserver-mcp http://127.0.0.1:9338/sse

Port Already in Use

# Error: Port 9338 is already in use! # Solution: Use a different port node dist/server.js --port 9339 --monitor pnpm run dev # Then connect with the new port claude mcp add --transport sse devserver-mcp http://127.0.0.1:9339/sse

No Real-Time Notifications

# Check MCP connection status claude mcp list # Remove and reconnect if needed claude mcp remove devserver-mcp claude mcp add --transport sse devserver-mcp http://127.0.0.1:9338/sse

Multiple Projects

# Each project should use a different port # Project A node dist/server.js --port 9338 --monitor pnpm run dev # Project B node dist/server.js --port 9339 --monitor npm run dev # Connect both in Claude Code with different names claude mcp add --transport sse project-a http://127.0.0.1:9338/sse claude mcp add --transport sse project-b http://127.0.0.1:9339/sse

License

MIT

DevServer MCP

DevServer MCP

Quick Start

Core Workflow

MCP Tools

Port Configuration

Architecture

Error Categories

Configuration

Development

Troubleshooting

Connection Failed

Port Already in Use

No Real-Time Notifications

Multiple Projects

License

Resources

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