MCP resources are read-only data exposed by MCP servers - docs, configurations, metadata - that Claude can reference and pull into context.

What it does

A server exposes resources by URI. Claude can list them, read them, and cite them in responses. Unlike tools (which do things) and prompts (which templatize), resources are content you bring into the session. This is how MCP servers publish reference material without asking Claude to keep calling tools to fetch it.

When to use it

Surfacing internal documentation for Claude to reason over.
Pulling configuration files from a config-as-service MCP.
Listing available items from a catalog server.
Making large, structured reference data available without custom tools.

Gotchas

Resources count against context when read. Watch the size.
Not all servers expose resources - capabilities vary.
Resource URIs aren't stable across server versions. Don't hard-code them in scripts.

Official docs: https://code.claude.com/docs/en/mcp.md#use-mcp-resources