diff --git a/src/server/mcp.ts b/src/server/mcp.ts
index cef1722d6..765ba864f 100644
--- a/src/server/mcp.ts
+++ b/src/server/mcp.ts
@@ -104,7 +104,8 @@ export class McpServer {
                             description: tool.description,
                             inputSchema: tool.inputSchema
                                 ? (zodToJsonSchema(tool.inputSchema, {
-                                      strictUnions: true
+                                      strictUnions: true,
+                                      pipeStrategy: 'input'
                                   }) as Tool['inputSchema'])
                                 : EMPTY_OBJECT_JSON_SCHEMA,
                             annotations: tool.annotations,
@@ -113,7 +114,8 @@ export class McpServer {
 
                         if (tool.outputSchema) {
                             toolDefinition.outputSchema = zodToJsonSchema(tool.outputSchema, {
-                                strictUnions: true
+                                strictUnions: true,
+                                pipeStrategy: 'output'
                             }) as Tool['outputSchema'];
                         }