Merge pull request modelcontextprotocol#357 from OpenLinkSoftware/main

When argument to a tool is not specified it should not be default and send via MCP request as a NULL value.

Author: olaservo

client/src/utils/__tests__/schemaUtils.test.ts

@@ -51,13 +51,13 @@ describe("generateDefaultValue", () => {
 
   test("generates null for non-required primitive types", () => {
     expect(generateDefaultValue({ type: "string", required: false })).toBe(
-      null,
+      undefined,
     );
     expect(generateDefaultValue({ type: "number", required: false })).toBe(
-      null,
+      undefined,
     );
     expect(generateDefaultValue({ type: "boolean", required: false })).toBe(
-      null,
+      undefined,
     );
   });
 

client/src/utils/schemaUtils.ts

@@ -13,7 +13,7 @@ export function generateDefaultValue(schema: JsonSchemaType): JsonValue {
   if (!schema.required) {
     if (schema.type === "array") return [];
     if (schema.type === "object") return {};
-    return null;
+    return undefined;
   }
 
   switch (schema.type) {