diff --git a/src/Api/ApiRegistry.php b/src/Api/ApiRegistry.php
index e815eb93..806847e3 100644
--- a/src/Api/ApiRegistry.php
+++ b/src/Api/ApiRegistry.php
@@ -71,13 +71,7 @@ public function getMethodDescriptor(string $method, ?ApiCallContext $context = n
             return null;
         }
 
-        return new MethodDescriptor(
-            name: $interface . '.' . $descriptor->name,
-            description: $descriptor->description,
-            parameters: $descriptor->parameters,
-            returnType: $descriptor->returnType,
-            permissions: $descriptor->permissions,
-        );
+        return $this->prefixDescriptor($interface, $descriptor);
     }
 
     /**
@@ -88,13 +82,7 @@ public function listMethods(?ApiCallContext $context = null): array
         $all = [];
         foreach ($this->providers as $interface => $provider) {
             foreach ($provider->listMethods($context) as $descriptor) {
-                $all[] = new MethodDescriptor(
-                    name: $interface . '.' . $descriptor->name,
-                    description: $descriptor->description,
-                    parameters: $descriptor->parameters,
-                    returnType: $descriptor->returnType,
-                    permissions: $descriptor->permissions,
-                );
+                $all[] = $this->prefixDescriptor($interface, $descriptor);
             }
         }
 
@@ -153,6 +141,24 @@ public function getProviderForInterface(string $interface): ApiProvider|MethodIn
         return $this->providers[$interface] ?? null;
     }
 
+    /**
+     * Re-wrap a provider-local descriptor with the interface-prefixed name,
+     * preserving all other metadata (including the JSON schemas needed by
+     * MCP tool listings).
+     */
+    private function prefixDescriptor(string $interface, MethodDescriptor $descriptor): MethodDescriptor
+    {
+        return new MethodDescriptor(
+            name: $interface . '.' . $descriptor->name,
+            description: $descriptor->description,
+            parameters: $descriptor->parameters,
+            returnType: $descriptor->returnType,
+            inputSchema: $descriptor->inputSchema,
+            outputSchema: $descriptor->outputSchema,
+            permissions: $descriptor->permissions,
+        );
+    }
+
     /**
      * @return array{string, string}|null
      */
diff --git a/test/Unit/Api/ApiRegistryTest.php b/test/Unit/Api/ApiRegistryTest.php
index c932b097..dc782a4b 100644
--- a/test/Unit/Api/ApiRegistryTest.php
+++ b/test/Unit/Api/ApiRegistryTest.php
@@ -85,6 +85,42 @@ public function testGetMethodDescriptorPrefixed(): void
         $this->assertSame('List items', $desc->description);
     }
 
+    public function testDescriptorSchemasPreserved(): void
+    {
+        $inputSchema = [
+            'type' => 'object',
+            'properties' => [
+                'pagename' => ['type' => 'string', 'description' => 'Page to edit'],
+            ],
+            'required' => ['pagename'],
+        ];
+        $outputSchema = ['type' => 'object'];
+        $provider = $this->makeProvider(
+            ['edit' => fn() => null],
+            ['edit' => new MethodDescriptor(
+                'edit',
+                description: 'Edit a page',
+                inputSchema: $inputSchema,
+                outputSchema: $outputSchema,
+            )],
+        );
+        $registry = new ApiRegistry();
+        $registry->registerProvider('wiki', $provider);
+
+        $desc = $registry->getMethodDescriptor('wiki.edit');
+
+        $this->assertNotNull($desc);
+        $this->assertSame($inputSchema, $desc->inputSchema);
+        $this->assertSame($outputSchema, $desc->outputSchema);
+
+        $listed = $registry->listMethods();
+
+        $this->assertCount(1, $listed);
+        $this->assertSame('wiki.edit', $listed[0]->name);
+        $this->assertSame($inputSchema, $listed[0]->inputSchema);
+        $this->assertSame($outputSchema, $listed[0]->outputSchema);
+    }
+
     public function testUnknownInterfaceHasMethodReturnsFalse(): void
     {
         $registry = new ApiRegistry();