How do MCP resources power a document mention feature?

Imagine a feature where users type the at sign followed by a document name to reference a file. This requires two operations. First, getting a list of all available documents so you can show an autocomplete dropdown. Second, fetching the contents of a specific document when one is mentioned. Both of these map cleanly onto resources. When the user actually mentions a document, your system fetches its contents through a resource and automatically injects them into the prompt sent to Claude, eliminating the need for Claude to make a separate tool call to fetch that information. The result is a faster, smoother experience.