devvit mcp

devvit-mcp

A companion MCP server for writing applications on Reddit's developer platform.

Installation

Add the following to your mcp.json for the editor or LLM of choice.

{
  "mcpServers": {
    "devvit-mcp": {
      "command": "npx",
      "args": ["-y", "@devvit/mcp"]
    }
  }
}

Opting Out Of Telemetry

{
  "mcpServers": {
    "devvit-mcp": {
      "command": "npx",
      "args": ["-y", "@devvit/mcp"],
      "env": {
        "DEVVIT_DISABLE_METRICS": "true"
      }
    }
  }
}

Developing on the MCP Server

git clone git@github.com:reddit/devvit-mcp.git

cd devvit-mcp

nvm use

npm install

npm run dev

If you want to test your MCP server inside of other projects. Pass in the entire path to your node runtime and the location of /dist/index.js on your machine.

• Node path: which node
• Dist: pwd from the root of your devvit-mcp + /dist/index.js

{
  "mcpServers": {
    "devvit-mcp": {
      "command": "/Users/marcus.wood/.nvm/versions/node/v22.13.0/bin/node",
      "args": ["/Users/marcus.wood/open-source/devvit-mcp/dist/index.js"]
    }
  }
}

MCP Gotchas

• Never put a console.log in the hot path of your app if you're trying to debug. You'll see weird error messages like Unexpected token 'a', " at Anthrop"... is not valid JSON. We've shimmed logger to automatically handle this conversion for you.
• Only log console.error in your MCP when running through MCP.

Debugging

• Using npm run dev, going to tools, listing them out, and triggering is the best experience.

• To test this live with logs, use Claude desktop and connecting the MCP there. They have log files that report errors on your machine. You can view them by opening in VSCode or running tail commands.

• If you see something like this:

Error: Server does not support logging (required for notifications/message)
    at Server.assertNotificationCapability

You need to add the capability to your new MCPServer. Use this permalink to know what key you should add.

Credits

Huge thanks to Arabold for open sourcing docs-mcp-server. Portions of this code is heavily inspired by this library. Please use it if you need other docs servers!