Connecting Letta to Local MCP Servers
Using stdio transport for local development
stdio is self-hosted only. Letta Cloud does not support stdio.
stdio transport launches MCP servers as local subprocesses, ideal for development and testing. Local (stdio) MCP servers can be useful for local development, testing, and situations where the MCP server you want to use is only available via stdio.
Setup
ADE: Tool Manager → Add MCP Server → stdio → specify command and args
Docker Support
Letta’s Docker image includes npx
, so npm-based MCP servers work out of the box. Custom Python scripts or missing dependencies require workarounds.
- Works in Docker:
npx
servers from the official MCP repository - Challenging: Custom scripts, local file paths, missing system dependencies
- Alternatives: Use remote servers or mcp-proxy
Troubleshooting
- Server won’t start: Check command path, dependencies, environment variables
- Connection fails: Review Letta logs, test command manually
- Tools missing: Verify MCP protocol implementation and tool registration