Merge branch 'feature/simplify-types' into update

README.md

@@ -59,6 +59,7 @@ openapi-mcp-generator --input path/to/openapi.json --output path/to/output/dir -
 | `--port`            | `-p`  | Port for web-based transports                                                                                                                  | `3000`                            |
 | `--default-include` |       | Default behavior for x-mcp filtering. Accepts `true` or `false` (case-insensitive). `true` = include by default, `false` = exclude by default. | `true`                            |
 | `--force`           |       | Overwrite existing files in the output directory without confirmation                                                                          | `false`                           |
+| `--simplifyTypes`  | `-st` | Flatten single-element type arrays in the JSON schema to their single value    | `false`                           |
 
 ## 📦 Programmatic API
 

src/generator/server-code.ts

@@ -25,7 +25,7 @@ export function generateMcpServerCode(
   serverVersion: string
 ): string {
   // Extract tools from API
-  const tools = extractToolsFromApi(api, options.defaultInclude ?? true);
+  const tools = extractToolsFromApi(api, options.defaultInclude ?? true, options.simplifyTypes);
 
   // Determine base URL
   const determinedBaseUrl = determineBaseUrl(api, options.baseUrl);

src/index.ts

@@ -87,6 +87,10 @@ program
     true
   )
   .option('--force', 'Overwrite existing files without prompting')
+  .option(
+    '-st, --simplifyTypes',
+    'Flatten single-element type arrays in the JSON schema to their single value'
+  )
   .version(pkg.version) // Match package.json version
   .action((options) => {
     runGenerator(options).catch((error) => {

src/parser/extract-tools.ts

@@ -15,7 +15,8 @@ import { shouldIncludeOperationForMcp } from '../utils/helpers.js';
  */
 export function extractToolsFromApi(
   api: OpenAPIV3.Document,
-  defaultInclude: boolean = true
+  defaultInclude: boolean = true,
+  simplifyTypes?: string,
 ): McpToolDefinition[] {
   const tools: McpToolDefinition[] = [];
   const usedNames = new Set<string>();
@@ -80,8 +81,10 @@ export function extractToolsFromApi(
         operation.description || operation.summary || `Executes ${method.toUpperCase()} ${path}`;
 
       // Generate input schema and extract parameters
-      const { inputSchema, parameters, requestBodyContentType } =
-        generateInputSchemaAndDetails(operation);
+      const { inputSchema, parameters, requestBodyContentType } = generateInputSchemaAndDetails(
+        operation,
+        simplifyTypes
+      );
 
       // Extract parameter details for execution
       const executionParameters = parameters.map((p) => ({ name: p.name, in: p.in }));
@@ -115,7 +118,10 @@ export function extractToolsFromApi(
  * @param operation OpenAPI operation object
  * @returns Input schema, parameters, and request body content type
  */
-export function generateInputSchemaAndDetails(operation: OpenAPIV3.OperationObject): {
+export function generateInputSchemaAndDetails(
+  operation: OpenAPIV3.OperationObject,
+  simplifyTypes?: string
+): {
   inputSchema: JSONSchema7 | boolean;
   parameters: OpenAPIV3.ParameterObject[];
   requestBodyContentType?: string;
@@ -131,7 +137,11 @@ export function generateInputSchemaAndDetails(operation: OpenAPIV3.OperationObje
   allParameters.forEach((param) => {
     if (!param.name || !param.schema) return;
 
-    const paramSchema = mapOpenApiSchemaToJsonSchema(param.schema as OpenAPIV3.SchemaObject);
+    const paramSchema = mapOpenApiSchemaToJsonSchema(
+      param.schema as OpenAPIV3.SchemaObject,
+      undefined,
+      simplifyTypes
+    );
     if (typeof paramSchema === 'object') {
       paramSchema.description = param.description || paramSchema.description;
     }
@@ -193,7 +203,8 @@ export function generateInputSchemaAndDetails(operation: OpenAPIV3.OperationObje
  */
 export function mapOpenApiSchemaToJsonSchema(
   schema: OpenAPIV3.SchemaObject | OpenAPIV3.ReferenceObject,
-  seen: WeakSet<object> = new WeakSet()
+  seen: WeakSet<object> = new WeakSet(),
+  simplifyTypes?: string
 ): JSONSchema7 | boolean {
   // Handle reference objects
   if ('$ref' in schema) {
@@ -238,6 +249,10 @@ export function mapOpenApiSchemaToJsonSchema(
       } else if (!jsonSchema.type) {
         jsonSchema.type = 'null';
       }
+    } else {
+      if (Array.isArray(jsonSchema.type) && jsonSchema.type.length === 1 && simplifyTypes) {
+        jsonSchema.type = jsonSchema.type[0];
+      }
     }
 
     // Recursively process object properties
@@ -248,7 +263,8 @@ export function mapOpenApiSchemaToJsonSchema(
         if (typeof propSchema === 'object' && propSchema !== null) {
           mappedProps[key] = mapOpenApiSchemaToJsonSchema(
             propSchema as OpenAPIV3.SchemaObject,
-            seen
+            seen,
+            simplifyTypes
           );
         } else if (typeof propSchema === 'boolean') {
           mappedProps[key] = propSchema;
@@ -266,7 +282,8 @@ export function mapOpenApiSchemaToJsonSchema(
     ) {
       jsonSchema.items = mapOpenApiSchemaToJsonSchema(
         jsonSchema.items as OpenAPIV3.SchemaObject | OpenAPIV3.ReferenceObject,
-        seen
+        seen,
+        simplifyTypes
       );
     }
     return jsonSchema;

src/types/index.ts

@@ -35,6 +35,8 @@ export interface CliOptions {
    * false = exclude by default unless x-mcp explicitly enables.
    */
   defaultInclude?: boolean;
+  /** Flatten single-element type arrays in the JSON schema to their single value */
+  simplifyTypes?: string;
 }
 
 /**