@modelcontextprotocol/server-everything/dist/tools/get-roots-list.js

MCP server that exercises all the features of the MCP protocol

// The `get-roots-list` tool: asks the client for its roots and lists them.
//
// Written once for both protocol eras with a multi-round-trip request
// (#4852): the first call returns `input_required` carrying a `roots/list`
// request, the client answers it and retries, and the retry lists the
// answer. A 2026-07-28 client does that in-band; for a 2025-era client the
// SDK's legacy shim sends a real `roots/list` request and re-enters the
// handler with the answer. Roots is deprecated as of 2026-07-28 (SEP-2577).
import { inputRequired, inputResponse, } from "@modelcontextprotocol/server";
import { TOOL_ICONS } from "../server/icons.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. " +
        "Deprecated: Roots is deprecated as of protocol version 2026-07-28. The server asks for the roots with a multi-round-trip request on every protocol version.",
    inputSchema: {},
    icons: TOOL_ICONS,
    annotations: {
        readOnlyHint: true,
        destructiveHint: false,
        idempotentHint: true,
        openWorldHint: false,
    },
};
/**
 * Registers the 'get-roots-list' tool.
 *
 * The tool needs a client that supports Roots: on a 2025-era connection the
 * server factory registers it only for one that declared the capability, and
 * on 2026-07-28 the SDK refuses the embedded request (-32021) of a client
 * whose request did not declare it.
 *
 * @param {McpServer} server - The McpServer instance where the tool will be registered.
 */
export const registerGetRootsListTool = (server) => {
    server.registerTool(name, config, async (_args, ctx) => {
        const answer = inputResponse(ctx.mcpReq.inputResponses, "roots");
        // First round: ask the client for its roots
        if (answer.kind !== "roots") {
            return inputRequired({
                inputRequests: { roots: inputRequired.listRoots() },
            });
        }
        const currentRoots = answer.roots;
        // Respond if client supports roots but doesn't have any configured
        if (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
            .map((root, index) => {
            return `${index + 1}. ${root.name || "Unnamed Root"}\n   URI: ${root.uri}`;
        })
            .join("\n\n");
        return {
            content: [
                {
                    type: "text",
                    text: `Current MCP Roots (${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.",
                },
            ],
        };
    });
};