Resource Templates List

👨‍💼 Our users want to be able to see a list of all tags. So let's implement the list callback for our resource templates.

import { ResourceTemplate } from '@modelcontextprotocol/sdk/server/mcp.js'

agent.server.registerResource(
	'hello',
	new ResourceTemplate('hello://{name}', {
		list: async () => {
			// Imagine this is a call to your database to get all names
			const names = await db.getAllNames()
			return {
				resources: names.map((name) => ({
					name,
					uri: `hello://${name}`,
					// NOTE: this mimeType is whatever the client should expect if it retrieves the resource
					mimeType: 'text/plain',
					// note this does not include the contents of the resource
				})),
			}
		},
	}),
	// ...
)

Notice how the list callback queries the database and returns a resource listing for each name. This pattern is exactly what you'll use to expose tags from your own database.

The reason for the list callback is to make it easy for clients to get a list of available resources without having to know the exact URIs and without having to request the entire resource (notice we only return the name, URI, and type in the list callback).

To test this out, click the "List Resources" button in the MCP Inspector.

03. Resources/03. Resource Templates List (💪 problem)

Resource Templates List