@@ -0,0 +1,25 @@
+import { describe, it, expect } from 'vitest';
+import { SearchNodesQuerySchema, SEARCH_QUERY_MAX_LENGTH } from '../index.js';
+
+describe('search_nodes input schema', () => {
+  it('should accept a normal query', () => {
+    expect(SearchNodesQuerySchema.safeParse('Alice').success).toBe(true);
+    expect(SearchNodesQuerySchema.safeParse('works at Acme Corp').success).toBe(true);
+  });
+
+  it('should accept a query at exactly the max length', () => {
+    const atLimit = 'a'.repeat(SEARCH_QUERY_MAX_LENGTH);
+    expect(SearchNodesQuerySchema.safeParse(atLimit).success).toBe(true);
+  });
+
+  it('should reject a query longer than the max length', () => {
+    const oversized = 'a'.repeat(SEARCH_QUERY_MAX_LENGTH + 1);
+    const result = SearchNodesQuerySchema.safeParse(oversized);
+    expect(result.success).toBe(false);
+  });
+
+  it('should still reject non-string input', () => {
+    expect(SearchNodesQuerySchema.safeParse(42).success).toBe(false);
+    expect(SearchNodesQuerySchema.safeParse(null).success).toBe(false);
+  });
+});
@@ -582,14 +582,21 @@ server.registerTool(
   }
 );
 
+export const SEARCH_QUERY_MAX_LENGTH = 2048;
+
+export const SearchNodesQuerySchema = z
+  .string()
+  .max(SEARCH_QUERY_MAX_LENGTH)
+  .describe("The search query to match against entity names, types, and observation content");
+
 // Register search_nodes tool
 server.registerTool(
   "search_nodes",
   {
     title: "Search Nodes",
     description: "Search for nodes in the knowledge graph based on a query",
     inputSchema: {
-      query: z.string().describe("The search query to match against entity names, types, and observation content")
+      query: SearchNodesQuerySchema
     },
     outputSchema: {
       entities: z.array(EntitySchema),