Reddit MCP Implementation Guide
A comprehensive walkthrough of the Model Context Protocol implementation with live SDK testing
OAuth Flow
Click "Connect with Reddit" to authenticate. You'll be redirected to Reddit for authorization, then back to this page to complete the flow.
Redirect URL: http://localhost:3001/mcp-implementation
Reddit MCP Server Implementation Guide
This guide documents the implementation of a production-ready Reddit MCP server using the Model Context Protocol SDK. The server provides comprehensive Reddit API integration through 10 MCP tools, implements OAuth 2.1 with PKCE for secure authentication, supports LLM sampling for AI-assisted content generation, and includes structured data validation with JSON Schema. Built with TypeScript and Express.js, this implementation serves as both a functional Reddit integration and a reference architecture for MCP servers.
Key Implementation Features
Core Capabilities
- • OAuth 2.1 flow with PKCE (S256) security
- • JWT-based session management
- • 10 Reddit API tools with full type safety
- • Streaming HTTP/SSE transport
- • Per-session authentication context
Advanced Features
- • Human-in-the-loop LLM sampling
- • Dynamic elicitation for user input
- • Real-time progress notifications
- • Comprehensive error handling
- • Rate limiting and request validation
Components
Architecture & Setup
Modular service architecture with Express.js HTTP server, MCP SDK integration via StreamableHTTPServerTransport, and facade pattern for Reddit API services.
Key Files: server.ts, server/mcp.ts, services/reddit/
OAuth 2.1 Integration
Complete OAuth 2.1 flow with PKCE (S256), dynamic client registration, JWT tokens containing Reddit credentials, and automatic token refresh.
Endpoints: /oauth/authorize, /oauth/token, /.well-known/*
Reddit API Tools
10 production-ready tools: search_reddit, get_post, get_channel, get_notifications, plus example tools for elicitation, sampling, and validation.
Validation: Zod schemas with comprehensive type safety
Prompts & Resources
8 MCP resources including Reddit config, API guidelines, code generation best practices, and dynamic server statistics.
Types: reddit://, guidelines://, template://, stats://
LLM Sampling & Elicitation
8-step human-in-the-loop sampling flow with callbacks, plus dynamic elicitation for collecting user input during tool execution.
Callbacks: suggest_action for Reddit content analysis
Progress Notifications
Real-time notifications for OAuth flow, long operations, sampling completion, and configuration changes with session targeting.
Types: message, progress, sampling/complete, config/changed
Best Practices
Production patterns: Custom error classes, Zod validation, rate limiting middleware, JWT security, and singleton services.
Security: PKCE, rate limits, request validation, CORS
Note: Interactive Testing Available
Each section includes interactive test buttons for validating your implementation. Connection testing and basic protocol operations are available above the tabs, while tool-specific tests are integrated within their respective sections.