diff --git a/src/client/input.ts b/src/client/input.ts
index cbfe9e1..d3e07fd 100644
--- a/src/client/input.ts
+++ b/src/client/input.ts
@@ -12,7 +12,7 @@ import { Buffer } from "buffer";
 import fs from "fs";
 
 export class Input extends Lister {
-  constructor({ authConfig }: { authConfig: AuthConfig }) {
+  constructor({ authConfig }: { authConfig?: AuthConfig }) {
     super({ authConfig });
   }
 
diff --git a/src/constants/search.ts b/src/constants/search.ts
new file mode 100644
index 0000000..f96471e
--- /dev/null
+++ b/src/constants/search.ts
@@ -0,0 +1,2 @@
+export const DEFAULT_TOP_K = 10;
+export const DEFAULT_SEARCH_METRIC = "cosine";
diff --git a/src/schema/search.ts b/src/schema/search.ts
new file mode 100644
index 0000000..c17e530
--- /dev/null
+++ b/src/schema/search.ts
@@ -0,0 +1,83 @@
+import { z } from "zod";
+
+/**
+ * Initialize the schema for rank and filter.
+ * This schema validates:
+ * - Rank and filter must be a list
+ * - Each item in the list must be a dict
+ * - The dict can contain these optional keys:
+ *   - 'image_url': Valid URL string
+ *   - 'text_raw': Non-empty string
+ *   - 'metadata': Dict
+ *   - 'image_bytes': Bytes
+ *   - 'geo_point': Dict with 'longitude', 'latitude' and 'geo_limit' as float, float and int respectively
+ *   - 'concepts': List where each item is a concept dict
+ * - Concept dict requires at least one of:
+ *   - 'name': Non-empty string with dashes/underscores
+ *   - 'id': Non-empty string
+ *   - 'language': Non-empty string
+ *   - 'value': 0 or 1 integer
+ * - 'input_types': List of 'image', 'video', 'text' or 'audio'
+ * - 'input_dataset_ids': List of strings
+ * - 'input_status_code': Integer
+ *
+ * @returns The schema for rank and filter, defining the structure and validation rules for each item.
+ */
+export function getSchema(): z.ZodSchema<
+  Array<{
+    imageUrl?: string;
+    textRaw?: string;
+    metadata?: Record<string, unknown>;
+    imageBytes?: unknown; // Note: TypeScript doesn't have a dedicated 'bytes' type, so 'unknown' is used
+    geoPoint?: {
+      longitude: number;
+      latitude: number;
+      geoLimit: number;
+    };
+    concepts?: Array<{
+      value?: number;
+      id?: string;
+      language?: string;
+      name?: string;
+    }>;
+    inputTypes?: Array<"image" | "video" | "text" | "audio">;
+    inputDatasetIds?: string[];
+    inputStatusCode?: number;
+  }>
+> {
+  // Schema for a single concept
+  const conceptSchema = z.object({
+    value: z.number().min(0).max(1).optional(),
+    id: z.string().min(1).optional(),
+    language: z.string().min(1).optional(),
+    name: z
+      .string()
+      .min(1)
+      .regex(/^[0-9A-Za-z]+([-_][0-9A-Za-z]+)*$/) // Non-empty string with dashes/underscores
+      .optional(),
+  });
+
+  // Schema for a rank or filter item
+  const rankFilterItemSchema = z.object({
+    imageUrl: z.string().url().optional(),
+    textRaw: z.string().min(1).optional(),
+    metadata: z.record(z.unknown()).optional(),
+    imageBytes: z.unknown().optional(),
+    geoPoint: z
+      .object({
+        longitude: z.number(),
+        latitude: z.number(),
+        geoLimit: z.number().int(),
+      })
+      .optional(),
+    concepts: z.array(conceptSchema).min(1).optional(),
+
+    // input filters
+    inputTypes: z.array(z.enum(["image", "video", "text", "audio"])).optional(),
+    inputDatasetIds: z.array(z.string()).optional(),
+    inputStatusCode: z.number().optional(),
+  });
+
+  // Schema for rank and filter args
+  return z.array(rankFilterItemSchema);
+}