MCP vs RAG: do you need both?

RAG retrieves text to put in the prompt; MCP connects a model to live tools and data. They solve different problems and work well together.

Short answer

RAG (retrieval-augmented generation) searches a document store and adds the best passages to the prompt. MCP lets the model call tools and read resources in other systems, including taking actions.

Using them together

A RAG pipeline can be exposed as an MCP tool (for example a search_docs tool), so any MCP client can use it. See the best MCP memory servers and the Memory & Knowledge category for servers that do this.

Rule of thumb

• Static knowledge to quote from: RAG.
• Live data, actions or many systems: MCP.