Reddit MCP Server

An MCP (Model Context Protocol) server that gives Claude access to Reddit. Browse subreddits, read posts and comments, search content, submit posts, comment, vote, and save — all from within Claude Code or any MCP-compatible client.

Features

12 tools covering the full Reddit experience:

Tool	Description
get_subreddit_posts	Get posts from a subreddit with sort/time filters and pagination
get_subreddit_info	Get subreddit metadata — subscribers, description, rules
search_posts	Search posts across Reddit or within a specific subreddit
search_subreddits	Search for subreddits by name or topic
read_post	Read a post and its comment tree with configurable depth
get_user_profile	Get a user's profile — karma, account age, bio
get_user_posts	Get posts submitted by a user
get_user_comments	Get comments posted by a user
submit_post	Submit a text or link post to a subreddit
submit_comment	Reply to a post or comment
vote	Upvote, downvote, or remove vote
save_post	Save or unsave a post or comment

Prerequisites

• Java 21 or later
• Maven 3.8+ (to build from source)
• A Reddit account

Setup

1. Create a Reddit app

1. Go to reddit.com/prefs/apps
2. Click "create another app..."
3. Fill in:
   • name: MCP (or anything you like)
   • type: select installed app
   • redirect uri: http://localhost:PORT/callback (the setup wizard will tell you the exact port)
4. Click create app
5. Copy the client ID shown under the app name

2. Build

git clone https://github.com/wrxck/reddit-mcp.git
cd reddit-mcp
mvn clean package -DskipTests

This produces target/reddit-mcp-1.0.0.jar — a self-contained executable JAR.

3. Run setup

java -jar target/reddit-mcp-1.0.0.jar --init

This will:

• Prompt for your Reddit client ID
• Save config to ~/.reddit-mcp/config.properties
• Open your browser for Reddit OAuth authorisation
• Save tokens to ~/.reddit-mcp/tokens.json
• Register the server with Claude Code automatically

4. Restart Claude Code

The reddit MCP server will be available in your next Claude Code session.

Usage

Once set up, Claude can use Reddit tools naturally:

> What's trending on r/programming right now?
> Search Reddit for discussions about MCP servers
> Read the comments on that top post
> What has u/spez posted recently?

Write operations require confirmation before executing:

> Upvote that post
> Reply to that comment with "Great explanation, thanks!"
> Submit a post to r/test titled "Hello from MCP"

Manual registration

If automatic registration didn't work, register manually:

claude mcp add --scope user --transport stdio reddit -- \
  java -jar /path/to/reddit-mcp-1.0.0.jar

Re-authenticate

If your Reddit tokens expire or you need to switch accounts:

java -jar target/reddit-mcp-1.0.0.jar --auth

Security

• Content sanitization — All Reddit content (titles, post bodies, comments, usernames) is wrapped in unique boundary markers with instructions to treat it as untrusted data. This defends against prompt injection via Reddit content.
• Token storage — OAuth tokens and config files are stored with 600 POSIX permissions (owner read/write only).
• Input validation — Subreddit names, usernames, and thing IDs are validated against strict regex patterns before any API call.
• CSRF protection — The OAuth flow uses cryptographic state parameters to prevent cross-site request forgery.

Rate limiting

The server enforces two layers of rate limiting:

1. Local — Max 55 requests/minute (below Reddit's 60/minute limit), tracked via a sliding window.
2. Server — Respects X-Ratelimit-Remaining and X-Ratelimit-Reset headers from Reddit. Automatically waits when approaching the server-side limit.

Building from source

mvn clean verify

This compiles, runs all 126 tests, and produces the shaded JAR.

Project structure

src/main/java/com/reddit/mcp/
├── RedditMcpServer.java     # Entry point, CLI args, server wiring
├── RedditClient.java        # HTTP client, token management, API methods
├── RedditAuth.java          # OAuth2 flow, config/token persistence
├── RedditTools.java         # 8 read-only MCP tool definitions
├── RedditWriteTools.java    # 4 write MCP tool definitions
├── ResponseParser.java      # Reddit JSON → structured maps
├── ContentSanitizer.java    # Prompt injection defence
├── Validation.java          # Input validation (regex patterns)
├── RateLimiter.java         # Dual-layer rate limiting
├── ResultHelper.java        # MCP result formatting utilities
└── ClaudeRegistration.java  # Auto-registration with Claude Code

License

MIT