Defining resources

MCP Resources: Document Mention Feature

**I. Core Concept & Purpose**

• Goal: To allow users to mention documents (e. g. , @report. pdf) within a message, enabling the system to automatically fetch and insert the document's content into the prompt sent to the LLM (Claude).
• Function: Resources allow the MCP server to expose specific data or read operations to the client.
• Feature Breakdown:
• Autocomplete: When the user types @, the MCP server must provide a list of all available document names.
• Content Fetch: When the user submits a message containing a mention, the MCP server must retrieve the content of that specific document.

**II. Resource Types**

• Direct (Static) Resources:
• Have a fixed, unchanging URI (e. g. , docs://documents).
• Used for operations that do not require user input parameters.
• Templated Resources:
• Contain one or more parameters or wildcards within the URI (e. g. , docs://documents/{doc_id}).
• The MCP Python SDK automatically parses these URI parameters and passes them as keyword arguments to the associated server function.
• Used for operations requiring selection or customization (e. g. , fetching a specific document).

**III. Implementation Workflow**

• Client Request: The client initiates a "Read Resource Request" by sending the defined URI to the MCP server.
• Server Execution: The MCP server uses the URI to locate and execute the corresponding function.
• Response: The server returns the data within a "Read Resource Result Message. "
• Data Handling: The client receives the result and handles the data based on the specified MIME type (e. g. , JSON or plain text).

**IV. Example Resource Definitions**

• Resource 1: List Documents (Static)
• URI: docs://documents
• MIME Type: application/json
• Function: Returns a list of all document IDs (keys) from the server's data structure.
• Resource 2: Fetch Document (Templated)
• URI: docs://documents/{doc_id}
• MIME Type: text/plain
• Function: Accepts doc_id as a keyword argument, verifies its existence, and returns the document's content as a string.

Takeaways

• MCP Resources allow users to mention documents (e. g. , @report. pdf) in messages, enabling the system to automatically fetch and insert the document's content into the LLM prompt.
• Resources are categorized as Direct (Static, fixed URI) or Templated (Parameterized, requires user input).
• Templated resources use URI parameters (e. g. , {doc_id}), which the MCP SDK automatically parses and passes as keyword arguments to the server function.
• The implementation workflow involves the client initiating a "Read Resource Request" and the MCP server responding with a "Read Resource Result Message. "