import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { CallToolResult } from "@modelcontextprotocol/sdk/types.js";
import { syncRoots } from "../server/roots.js";
// Tool configuration
const name = "get-roots-list";
const config = {
title: "Get Roots List Tool",
description:
"Lists the current MCP roots provided by the client. Demonstrates the roots protocol capability even though this server doesn't access files.",
inputSchema: {},
};
/**
* Registers the 'get-roots-list' tool.
*
* If the client does not support the roots capability, the tool is not registered.
*
* The registered tool interacts with the MCP roots capability, which enables the server to access
* information about the client's workspace directories or file system roots.
*
* When supported, the server automatically retrieves and formats the current list of roots from the
* client upon connection and whenever the client sends a `roots/list_changed` notification.
*
* Therefore, this tool displays the roots that the server currently knows about for the connected
* client. If for some reason the server never got the initial roots list, the tool will request the
* list from the client again.
*
* @param {McpServer} server - The McpServer instance where the tool will be registered.
*/
export const registerGetRootsListTool = (server: McpServer) => {
// Does client support roots?
const clientCapabilities = server.server.getClientCapabilities() || {};
const clientSupportsRoots: boolean = clientCapabilities.roots !== undefined;
// If so, register tool
if (clientSupportsRoots) {
server.registerTool(
name,
config,
async (args, extra): Promise<CallToolResult> => {
// Get the current rootsFetch the current roots list from the client if need be
const currentRoots = await syncRoots(server, extra.sessionId);
// Respond if client supports roots but doesn't have any configured
if (
clientSupportsRoots &&
(!currentRoots || currentRoots.length === 0)
) {
return {
content: [
{
type: "text",
text:
"The client supports roots but no roots are currently configured.\n\n" +
"This could mean:\n" +
"1. The client hasn't provided any roots yet\n" +
"2. The client provided an empty roots list\n" +
"3. The roots configuration is still being loaded",
},
],
};
}
// Create formatted response if there is a list of roots
const rootsList = currentRoots
? currentRoots
.map((root, index) => {
return `${index + 1}. ${root.name || "Unnamed Root"}\n URI: ${
root.uri
}`;
})
.join("\n\n")
: "No roots found";
return {
content: [
{
type: "text",
text:
`Current MCP Roots (${
currentRoots!.length
} total):\n\n${rootsList}\n\n` +
"Note: This server demonstrates the roots protocol capability but doesn't actually access files. " +
"The roots are provided by the MCP client and can be used by servers that need file system access.",
},
],
};
}
);
}
};
