fix: pass both args when inputSchema omitted in task handler executor

When inputSchema is undefined, createToolExecutor now calls
taskHandler.createTask({}, taskCtx) instead of casting to a
single-arg signature. This ensures two-argument handlers receive
correct argument positions: (args, ctx) rather than having
ctx shifted to the first parameter.

Regular tool callbacks remain unchanged — their single-arg
signature matches the TypeScript types.

Fixes #1471

Author: nanookclaw

packages/server/src/server/mcp.ts

@@ -1120,7 +1120,9 @@ export type RegisteredTool = {
 /**
  * Creates an executor that invokes the handler with the appropriate arguments.
  * When `inputSchema` is defined, the handler is called with `(args, ctx)`.
- * When `inputSchema` is undefined, the handler is called with just `(ctx)`.
+ * When `inputSchema` is undefined, regular tool callbacks are called with `(ctx)`.
+ * Task handlers are always called with `(args, ctx)`, passing `{}` when inputSchema is undefined,
+ * to match the two-argument handler signature.
  */
 function createToolExecutor(
     inputSchema: StandardSchemaWithJSON | undefined,
@@ -1138,8 +1140,8 @@ function createToolExecutor(
             if (inputSchema) {
                 return taskHandler.createTask(args, taskCtx);
             }
-            // When no inputSchema, call with just ctx (the handler expects (ctx) signature)
-            return (taskHandler.createTask as (ctx: CreateTaskServerContext) => CreateTaskResult | Promise<CreateTaskResult>)(taskCtx);
+            // When no inputSchema, pass empty object as args so two-argument handlers receive correct positions
+            return taskHandler.createTask({}, taskCtx);
         };
     }
 

test/integration/test/server/mcp.test.ts

@@ -6828,7 +6828,7 @@ describe('Zod v4', () => {
                     }
                 },
                 {
-                    createTask: async ctx => {
+                    createTask: async (_args, ctx) => {
                         const task = await ctx.task.store.createTask({ ttl: 60_000, pollInterval: 100 });
 
                         // Capture taskStore for use in setTimeout
@@ -6932,7 +6932,7 @@ describe('Zod v4', () => {
                     }
                 },
                 {
-                    createTask: async ctx => {
+                    createTask: async (_args, ctx) => {
                         const task = await ctx.task.store.createTask({ ttl: 60_000, pollInterval: 100 });
 
                         // Capture taskStore for use in setTimeout