fix(mcp): harden tool schemas and dispatch (#6815)

apps/nextjs/src/app/api/mcp/_protocol.ts

@@ -1,5 +1,6 @@
-import { createMcpHandler, McpServer } from "@modelcontextprotocol/server";
+import { createMcpHandler, fromJsonSchema, McpServer } from "@modelcontextprotocol/server";
 
+import { callMcpTool } from "@homarr/api/mcp";
 import type { McpTool } from "@homarr/api/mcp";
 
 import { toAssistantToolOutput } from "../assistant/chat/assistant-tool-output";
@@ -15,15 +16,6 @@ interface CreateMcpProtocolHandlerOptions {
   onProtocolError?: (error: Error) => void;
 }
 
-const resolveProcedure = (caller: unknown, path: string[]) =>
-  path.reduce<unknown>(
-    (current, segment) =>
-      (typeof current === "object" || typeof current === "function") && current !== null
-        ? (current as Record<string, unknown>)[segment]
-        : undefined,
-    caller,
-  );
-
 export const createMcpProtocolHandler = ({
   caller,
   tools,
@@ -52,20 +44,11 @@ export const createMcpProtocolHandler = ({
           tool.name,
           {
             description: tool.description,
-            inputSchema: tool.inputValidator,
+            inputSchema: fromJsonSchema(tool.inputSchema as Parameters<typeof fromJsonSchema>[0]),
           },
           async (args) => {
             try {
-              const procedure = resolveProcedure(caller, tool.pathInRouter);
-              if (typeof procedure !== "function") {
-                return {
-                  content: [{ type: "text" as const, text: `Tool "${tool.name}" is not callable` }],
-                  isError: true,
-                };
-              }
-
-              const input = Object.keys(args).length > 0 ? args : undefined;
-              const result = await (procedure as (value: unknown) => Promise<unknown>)(input);
+              const result = await callMcpTool(caller, tool, args);
               return {
                 content: [
                   {