diff --git a/src/index.ts b/src/index.ts
index ef1b31a..1e1f17d 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -28,7 +28,7 @@ function createEChartsServer(): McpServer {
   for (const tool of tools) {
     const { name, description, inputSchema, run } = tool;
     // biome-ignore lint/suspicious/noExplicitAny: <explanation>
-    server.tool(name, description, inputSchema.shape, run as any);
+    server.tool(name, description, inputSchema.shape as any, run as any);
   }
 
   return server;
diff --git a/src/utils/schema.ts b/src/utils/schema.ts
index 3052829..9631489 100644
--- a/src/utils/schema.ts
+++ b/src/utils/schema.ts
@@ -49,9 +49,9 @@ export const WidthSchema = z
   .describe("Set the width of the chart, default is 800px.");
 
 // TODO: use zod v4 JSON to schema to replace zod-to-json-schema when v4 is stable
-// biome-ignore lint/suspicious/noExplicitAny: <explanation>
-export const zodToJsonSchema = (schema: z.ZodType<any>) => {
-  return zodToJsonSchemaOriginal(schema, {
+export const zodToJsonSchema = (schema: unknown): Record<string, unknown> => {
+  // biome-ignore lint/suspicious/noExplicitAny: Type assertion needed to avoid TypeScript deep type instantiation
+  return zodToJsonSchemaOriginal(schema as any, {
     rejectedAdditionalProperties: undefined,
   });
 };