diff --git a/server/langchain-tools.js b/server/langchain-tools.js
index 4cb77313..3ca1128d 100644
--- a/server/langchain-tools.js
+++ b/server/langchain-tools.js
@@ -2,9 +2,20 @@ import { DynamicStructuredTool } from '@langchain/core/tools';
 import { z } from 'zod';
 import axios from 'axios';
 
-const BASE_URL = 'http://localhost:3000/api';
+const BASE_URL = process.env.SWAPI_BASE_URL || 'http://localhost:3000/api';
 
-// Helper function to create detailed API call information
+// Constants for search functionality
+const SEARCH_COLORS = ['red', 'blue', 'green', 'yellow', 'brown', 'black', 'white', 'orange', 'purple', 'pink', 'blond', 'blonde', 'fair', 'dark', 'light'];
+
+/**
+ * Helper function to create detailed API call information for tracking and debugging
+ * @param {string} method - HTTP method used for the API call
+ * @param {string} url - The URL that was called
+ * @param {Object} params - Query parameters sent with the request
+ * @param {Object} data - Request body data (if any)
+ * @param {Error} error - Error object if the request failed
+ * @returns {Object} Structured API call information object
+ */
 function createApiCallInfo(method, url, params, data, error) {
   return {
     method,
@@ -16,7 +27,12 @@ function createApiCallInfo(method, url, params, data, error) {
   };
 }
 
-// Wrapper function to capture API call details
+/**
+ * Wrapper function to capture API call details and handle errors consistently
+ * @param {string} url - The API endpoint URL to call
+ * @param {Object} params - Query parameters to include (default: {})
+ * @returns {Promise<Object>} Object with success flag, data, and API call information
+ */
 async function makeApiCall(url, params = {}) {
   const apiCallInfo = createApiCallInfo('GET', url, params);
   try {
@@ -47,6 +63,14 @@ export const getCharacterTool = new DynamicStructuredTool({
     id: z.number().describe('The ID of the character to retrieve')
   }),
   func: async ({ id }) => {
+    // Basic input validation
+    if (!Number.isInteger(id) || id <= 0) {
+      return JSON.stringify({
+        error: `Invalid character ID: ${id}. ID must be a positive integer.`,
+        apiCall: createApiCallInfo('GET', `${BASE_URL}/characters/${id}`, {}, null, new Error('Invalid ID'))
+      }, null, 2);
+    }
+
     const result = await makeApiCall(`${BASE_URL}/characters/${id}`);
     if (result.success) {
       // Include API call information in the response for educational purposes
@@ -332,21 +356,21 @@ export const searchCharactersTool = new DynamicStructuredTool({
       let matchedCharacters = [];
       
       if (attributeLower.includes('eye')) {
-        const color = attributeLower.match(/(red|blue|green|yellow|brown|black|white|orange|purple|pink)/)?.[1];
+        const color = attributeLower.match(new RegExp(`(${SEARCH_COLORS.join('|')})`))?.[1];
         if (color) {
           matchedCharacters = characters.filter(char => 
             char.eye_color && char.eye_color.toLowerCase().includes(color)
           );
         }
       } else if (attributeLower.includes('hair')) {
-        const color = attributeLower.match(/(red|blue|green|yellow|brown|black|white|orange|purple|pink|blond|blonde)/)?.[1];
+        const color = attributeLower.match(new RegExp(`(${SEARCH_COLORS.join('|')})`))?.[1];
         if (color) {
           matchedCharacters = characters.filter(char => 
             char.hair_color && char.hair_color.toLowerCase().includes(color)
           );
         }
       } else if (attributeLower.includes('skin')) {
-        const color = attributeLower.match(/(red|blue|green|yellow|brown|black|white|orange|purple|pink|fair|dark|light)/)?.[1];
+        const color = attributeLower.match(new RegExp(`(${SEARCH_COLORS.join('|')})`))?.[1];
         if (color) {
           matchedCharacters = characters.filter(char => 
             char.skin_color && char.skin_color.toLowerCase().includes(color)
@@ -402,7 +426,11 @@ export const swapiTools = [
   searchCharactersTool
 ];
 
-// Helper function to extract entity IDs from vector search results
+/**
+ * Helper function to extract entity IDs from vector search results
+ * @param {Array} context - Array of vector search result objects with metadata
+ * @returns {Object} Object containing arrays of entity IDs grouped by entity type
+ */
 export function extractEntityIds(context) {
   const entityIds = {
     characters: [],
diff --git a/server/tests/langchain-tools-validation.test.js b/server/tests/langchain-tools-validation.test.js
new file mode 100644
index 00000000..6d580340
--- /dev/null
+++ b/server/tests/langchain-tools-validation.test.js
@@ -0,0 +1,42 @@
+import { jest } from '@jest/globals';
+import { getCharacterTool } from '../langchain-tools.js';
+
+describe('LangChain Tools Input Validation', () => {
+  describe('getCharacterTool input validation', () => {
+    it('should reject invalid ID (negative number)', async () => {
+      const result = await getCharacterTool.func({ id: -1 });
+      const parsed = JSON.parse(result);
+      
+      expect(parsed.error).toBeDefined();
+      expect(parsed.error).toContain('Invalid character ID');
+      expect(parsed.error).toContain('-1');
+    });
+
+    it('should reject invalid ID (zero)', async () => {
+      const result = await getCharacterTool.func({ id: 0 });
+      const parsed = JSON.parse(result);
+      
+      expect(parsed.error).toBeDefined();
+      expect(parsed.error).toContain('Invalid character ID');
+      expect(parsed.error).toContain('0');
+    });
+
+    it('should reject invalid ID (non-integer)', async () => {
+      const result = await getCharacterTool.func({ id: 1.5 });
+      const parsed = JSON.parse(result);
+      
+      expect(parsed.error).toBeDefined();
+      expect(parsed.error).toContain('Invalid character ID');
+      expect(parsed.error).toContain('1.5');
+    });
+
+    it('should include API call info for invalid IDs', async () => {
+      const result = await getCharacterTool.func({ id: -1 });
+      const parsed = JSON.parse(result);
+      
+      expect(parsed.apiCall).toBeDefined();
+      expect(parsed.apiCall.error).toContain('Invalid ID');
+      expect(parsed.apiCall.method).toBe('GET');
+    });
+  });
+});
\ No newline at end of file