diff --git a/package.json b/package.json
index 99389da..09a33ee 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "@anthropic-ai/mcpb",
   "description": "Tools for building MCP Bundles",
-  "version": "2.1.1",
+  "version": "2.1.2",
   "type": "module",
   "main": "dist/index.js",
   "module": "dist/index.js",
diff --git a/schemas/mcpb-manifest-v0.4.schema.json b/schemas/mcpb-manifest-v0.4.schema.json
index 69496ba..5917415 100644
--- a/schemas/mcpb-manifest-v0.4.schema.json
+++ b/schemas/mcpb-manifest-v0.4.schema.json
@@ -188,7 +188,8 @@
       },
       "required": [
         "type",
-        "entry_point"
+        "entry_point",
+        "mcp_config"
       ],
       "additionalProperties": false
     },
diff --git a/src/schemas/0.4.ts b/src/schemas/0.4.ts
index e706e26..e044b91 100644
--- a/src/schemas/0.4.ts
+++ b/src/schemas/0.4.ts
@@ -37,8 +37,7 @@ export const McpbManifestMcpConfigSchema = McpServerConfigSchema.extend({
 export const McpbManifestServerSchema = z.strictObject({
   type: z.enum(["python", "node", "binary", "uv"]),
   entry_point: z.string(),
-  // mcp_config is optional for UV type (UV handles execution)
-  mcp_config: McpbManifestMcpConfigSchema.optional(),
+  mcp_config: McpbManifestMcpConfigSchema,
 });
 
 export const McpbManifestCompatibilitySchema = z.strictObject({