diff --git a/apps/sim/app/api/knowledge/route.ts b/apps/sim/app/api/knowledge/route.ts
index 07d439fe8..9aaf52b5a 100644
--- a/apps/sim/app/api/knowledge/route.ts
+++ b/apps/sim/app/api/knowledge/route.ts
@@ -19,7 +19,7 @@ const logger = createLogger('KnowledgeBaseAPI')
 const CreateKnowledgeBaseSchema = z.object({
   name: z.string().min(1, 'Name is required'),
   description: z.string().optional(),
-  workspaceId: z.string().optional(),
+  workspaceId: z.string().min(1, 'Workspace ID is required'),
   embeddingModel: z.literal('text-embedding-3-small').default('text-embedding-3-small'),
   embeddingDimension: z.literal(1536).default(1536),
   chunkingConfig: z
diff --git a/apps/sim/lib/copilot/tools/server/knowledge/knowledge-base.ts b/apps/sim/lib/copilot/tools/server/knowledge/knowledge-base.ts
index 853638d89..d6d5af7ba 100644
--- a/apps/sim/lib/copilot/tools/server/knowledge/knowledge-base.ts
+++ b/apps/sim/lib/copilot/tools/server/knowledge/knowledge-base.ts
@@ -37,6 +37,13 @@ export const knowledgeBaseServerTool: BaseServerTool<KnowledgeBaseArgs, Knowledg
             }
           }
 
+          if (!args.workspaceId) {
+            return {
+              success: false,
+              message: 'Workspace ID is required for creating a knowledge base',
+            }
+          }
+
           const requestId = crypto.randomUUID().slice(0, 8)
           const newKnowledgeBase = await createKnowledgeBase(
             {
diff --git a/apps/sim/lib/copilot/tools/shared/schemas.ts b/apps/sim/lib/copilot/tools/shared/schemas.ts
index 31fed5417..2377aecf7 100644
--- a/apps/sim/lib/copilot/tools/shared/schemas.ts
+++ b/apps/sim/lib/copilot/tools/shared/schemas.ts
@@ -79,7 +79,7 @@ export const KnowledgeBaseArgsSchema = z.object({
       name: z.string().optional(),
       /** Description of the knowledge base (optional for create) */
       description: z.string().optional(),
-      /** Workspace ID to associate with (optional for create/list) */
+      /** Workspace ID to associate with (required for create, optional for list) */
       workspaceId: z.string().optional(),
       /** Knowledge base ID (required for get, query) */
       knowledgeBaseId: z.string().optional(),
diff --git a/apps/sim/lib/knowledge/service.ts b/apps/sim/lib/knowledge/service.ts
index 6b2572a2f..d065ed569 100644
--- a/apps/sim/lib/knowledge/service.ts
+++ b/apps/sim/lib/knowledge/service.ts
@@ -86,18 +86,16 @@ export async function createKnowledgeBase(
   const kbId = randomUUID()
   const now = new Date()
 
-  if (data.workspaceId) {
-    const hasPermission = await getUserEntityPermissions(data.userId, 'workspace', data.workspaceId)
-    if (hasPermission === null) {
-      throw new Error('User does not have permission to create knowledge bases in this workspace')
-    }
+  const hasPermission = await getUserEntityPermissions(data.userId, 'workspace', data.workspaceId)
+  if (hasPermission === null) {
+    throw new Error('User does not have permission to create knowledge bases in this workspace')
   }
 
   const newKnowledgeBase = {
     id: kbId,
     name: data.name,
     description: data.description ?? null,
-    workspaceId: data.workspaceId ?? null,
+    workspaceId: data.workspaceId,
     userId: data.userId,
     tokenCount: 0,
     embeddingModel: data.embeddingModel,
@@ -122,7 +120,7 @@ export async function createKnowledgeBase(
     chunkingConfig: data.chunkingConfig,
     createdAt: now,
     updatedAt: now,
-    workspaceId: data.workspaceId ?? null,
+    workspaceId: data.workspaceId,
     docCount: 0,
   }
 }
diff --git a/apps/sim/lib/knowledge/types.ts b/apps/sim/lib/knowledge/types.ts
index 8516b6e70..f962a65fb 100644
--- a/apps/sim/lib/knowledge/types.ts
+++ b/apps/sim/lib/knowledge/types.ts
@@ -32,7 +32,7 @@ export interface KnowledgeBaseWithCounts {
 export interface CreateKnowledgeBaseData {
   name: string
   description?: string
-  workspaceId?: string
+  workspaceId: string
   embeddingModel: 'text-embedding-3-small'
   embeddingDimension: 1536
   chunkingConfig: ChunkingConfig