diff --git a/packages/core/src/execution-engine/node-execution-context/utils/__tests__/create-node-as-tool.test.ts b/packages/core/src/execution-engine/node-execution-context/utils/__tests__/create-node-as-tool.test.ts
index 1a014933bf..0a71034fa5 100644
--- a/packages/core/src/execution-engine/node-execution-context/utils/__tests__/create-node-as-tool.test.ts
+++ b/packages/core/src/execution-engine/node-execution-context/utils/__tests__/create-node-as-tool.test.ts
@@ -115,6 +115,73 @@ describe('createNodeAsTool', () => {
 			expect(tool.schema.shape.booleanWithDefault.description).toBe('Boolean with default');
 		});
 
+		it('should allow omitting parameters with default values', () => {
+			node.parameters = {
+				requiredParam: "={{ $fromAI('requiredParam', 'Required parameter', 'string') }}",
+				optionalParam:
+					"={{ $fromAI('optionalParam', 'Optional parameter', 'string', 'default value') }}",
+				optionalNumber: "={{ $fromAI('optionalNumber', 'Optional number', 'number', 42) }}",
+			};
+
+			const tool = createNodeAsTool(options).response;
+
+			// Test that the schema accepts an object with only the required field
+			// This should NOT throw an error if fields with defaults are truly optional
+			const parseResult = tool.schema.safeParse({ requiredParam: 'test' });
+
+			expect(parseResult.success).toBe(true);
+			if (parseResult.success) {
+				expect(parseResult.data.requiredParam).toBe('test');
+				expect(parseResult.data.optionalParam).toBe('default value');
+				expect(parseResult.data.optionalNumber).toBe(42);
+			}
+
+			// Test that all fields can still be provided
+			const fullParseResult = tool.schema.safeParse({
+				requiredParam: 'test',
+				optionalParam: 'custom value',
+				optionalNumber: 100,
+			});
+
+			expect(fullParseResult.success).toBe(true);
+			if (fullParseResult.success) {
+				expect(fullParseResult.data.requiredParam).toBe('test');
+				expect(fullParseResult.data.optionalParam).toBe('custom value');
+				expect(fullParseResult.data.optionalNumber).toBe(100);
+			}
+		});
+
+		it('should allow omitting parameters with default values = empty string', () => {
+			node.parameters = {
+				requiredParam: "={{ $fromAI('requiredParam', 'Required parameter', 'string') }}",
+				optionalParam: "={{ $fromAI('optionalParam', 'Optional parameter', 'string', '') }}",
+			};
+
+			const tool = createNodeAsTool(options).response;
+
+			// Test that the schema accepts an object with only the required field
+			// This should NOT throw an error if fields with defaults are truly optional
+			const parseResult = tool.schema.safeParse({ requiredParam: 'test' });
+
+			expect(parseResult.success).toBe(true);
+			if (parseResult.success) {
+				expect(parseResult.data.requiredParam).toBe('test');
+				expect(parseResult.data.optionalParam).toBe('');
+			}
+
+			// Test that all fields can still be provided
+			const fullParseResult = tool.schema.safeParse({
+				requiredParam: 'test',
+				optionalParam: 'custom value',
+			});
+
+			expect(fullParseResult.success).toBe(true);
+			if (fullParseResult.success) {
+				expect(fullParseResult.data.requiredParam).toBe('test');
+				expect(fullParseResult.data.optionalParam).toBe('custom value');
+			}
+		});
+
 		it('should handle nested parameters correctly', () => {
 			node.parameters = {
 				topLevel: "={{ $fromAI('topLevel', 'Top level parameter', 'string') }}",
diff --git a/packages/workflow/src/from-ai-parse-utils.ts b/packages/workflow/src/from-ai-parse-utils.ts
index 8ad82f9e09..9131af6457 100644
--- a/packages/workflow/src/from-ai-parse-utils.ts
+++ b/packages/workflow/src/from-ai-parse-utils.ts
@@ -104,19 +104,32 @@ export function generateZodSchema(placeholder: FromAIArgument): z.ZodTypeAny {
 	return schema;
 }
 
+function isFromAIArgumentType(value: string): value is FromAIArgumentType {
+	return ['string', 'number', 'boolean', 'json'].includes(value.toLowerCase());
+}
+
 /**
  * Parses the default value, preserving its original type.
  * @param value The default value as a string.
+ * @param type The expected type of the default value.
  * @returns The parsed default value in its appropriate type.
  */
 function parseDefaultValue(
 	value: string | undefined,
+	type: FromAIArgumentType = 'string',
 ): string | number | boolean | Record<string, unknown> | undefined {
-	if (value === undefined || value === '') return undefined;
+	if (value === undefined) return value;
+
 	const lowerValue = value.toLowerCase();
-	if (lowerValue === 'true') return true;
-	if (lowerValue === 'false') return false;
-	if (!isNaN(Number(value))) return Number(value);
+	if (type === 'string') {
+		return value.toString();
+	}
+
+	if (type === 'boolean' && (lowerValue === 'true' || lowerValue === 'false'))
+		return lowerValue === 'true';
+	if (type === 'number' && !isNaN(Number(value))) return Number(value);
+
+	// For type 'json' or any other case, attempt to parse as JSON
 	try {
 		return jsonParse(value);
 	} catch {
@@ -197,17 +210,17 @@ function parseArguments(argsString: string): FromAIArgument {
 		return trimmed;
 	});
 
-	const type = cleanArgs?.[2] || 'string';
+	const type = cleanArgs?.[2] ?? 'string';
 
-	if (!['string', 'number', 'boolean', 'json'].includes(type.toLowerCase())) {
+	if (!isFromAIArgumentType(type)) {
 		throw new ParseError(`Invalid type: ${type}`);
 	}
 
 	return {
 		key: cleanArgs[0] || '',
 		description: cleanArgs[1],
-		type: (cleanArgs?.[2] ?? 'string') as FromAIArgumentType,
-		defaultValue: parseDefaultValue(cleanArgs[3]),
+		type,
+		defaultValue: parseDefaultValue(cleanArgs[3], type),
 	};
 }
 
diff --git a/packages/workflow/test/from-ai-parse-utils.test.ts b/packages/workflow/test/from-ai-parse-utils.test.ts
index fd5fdbf7f3..734bc18969 100644
--- a/packages/workflow/test/from-ai-parse-utils.test.ts
+++ b/packages/workflow/test/from-ai-parse-utils.test.ts
@@ -11,10 +11,19 @@ describe('extractFromAICalls', () => {
 	test.each<[string, [unknown, unknown, unknown, unknown]]>([
 		['$fromAI("a", "b", "string")', ['a', 'b', 'string', undefined]],
 		['$fromAI("a", "b", "number", 5)', ['a', 'b', 'number', 5]],
+		['$fromAI("a", "b", "number", "5")', ['a', 'b', 'number', 5]],
 		['$fromAI("a", "`", "number", 5)', ['a', '`', 'number', 5]],
 		['$fromAI("a", "\\`", "number", 5)', ['a', '`', 'number', 5]], // this is a bit surprising, but intended
 		['$fromAI("a", "\\n", "number", 5)', ['a', 'n', 'number', 5]], // this is a bit surprising, but intended
 		['{{ $fromAI("a", "b", "boolean") }}', ['a', 'b', 'boolean', undefined]],
+		['{{ $fromAI("a", "b", "boolean", "true") }}', ['a', 'b', 'boolean', true]],
+		['{{ $fromAI("a", "b", "boolean", "false") }}', ['a', 'b', 'boolean', false]],
+		['{{ $fromAI("a", "b", "boolean", true) }}', ['a', 'b', 'boolean', true]],
+		['{{ $fromAI("a", "b", "string", "") }}', ['a', 'b', 'string', '']],
+		['{{ $fromAI("a", "b", "string", "null") }}', ['a', 'b', 'string', 'null']],
+		['{{ $fromAI("a", "b", "string", "5") }}', ['a', 'b', 'string', '5']],
+		['{{ $fromAI("a", "b", "string", "true") }}', ['a', 'b', 'string', 'true']],
+		['{{ $fromAI("a", "b", "string", "{}") }}', ['a', 'b', 'string', '{}']],
 	])('should parse args as expected for %s', (formula, [key, description, type, defaultValue]) => {
 		expect(extractFromAICalls(formula)).toEqual([
 			{