feat: implement expand-task MCP command

- Create direct function wrapper in expand-task.js with error handling

- Add MCP tool integration for breaking down tasks into subtasks

- Update task-master-core.js to expose expandTaskDirect function

- Update changeset to document the new command

- Parameter support for subtask generation options (num, research, prompt, force)

mcp-server/src/tools/expand-task.js

@@ -0,0 +1,57 @@
+/**
+ * tools/expand-task.js
+ * Tool to expand a task into subtasks
+ */
+
+import { z } from "zod";
+import {
+  handleApiResult,
+  createErrorResponse
+} from "./utils.js";
+import { expandTaskDirect } from "../core/task-master-core.js";
+
+/**
+ * Register the expand-task tool with the MCP server
+ * @param {Object} server - FastMCP server instance
+ */
+export function registerExpandTaskTool(server) {
+  server.addTool({
+    name: "expand_task",
+    description: "Expand a task into subtasks for detailed implementation",
+    parameters: z.object({
+      id: z.string().describe("ID of task to expand"),
+      num: z.union([z.number(), z.string()]).optional().describe("Number of subtasks to generate"),
+      research: z.boolean().optional().describe("Use Perplexity AI for research-backed generation"),
+      prompt: z.string().optional().describe("Additional context for subtask generation"),
+      force: z.boolean().optional().describe("Force regeneration even for tasks that already have subtasks"),
+      file: z.string().optional().describe("Path to the tasks file"),
+      projectRoot: z
+        .string()
+        .optional()
+        .describe(
+          "Root directory of the project (default: current working directory)"
+        ),
+    }),
+    execute: async (args, { log }) => {
+      try {
+        log.info(`Expanding task with args: ${JSON.stringify(args)}`);
+        
+        // Call the direct function wrapper
+        const result = await expandTaskDirect(args, log);
+        
+        // Log result
+        if (result.success) {
+          log.info(`Successfully expanded task ID: ${args.id} with ${result.data.subtasksAdded} new subtasks${result.data.hasExistingSubtasks ? ' (appended to existing subtasks)' : ''}`);
+        } else {
+          log.error(`Failed to expand task: ${result.error.message}`);
+        }
+        
+        // Use handleApiResult to format the response
+        return handleApiResult(result, log, 'Error expanding task');
+      } catch (error) {
+        log.error(`Error in expand-task tool: ${error.message}`);
+        return createErrorResponse(`Failed to expand task: ${error.message}`);
+      }
+    },
+  });
+} 

mcp-server/src/tools/index.js

@@ -13,6 +13,7 @@ import { registerUpdateSubtaskTool } from "./update-subtask.js";
 import { registerGenerateTool } from "./generate.js";
 import { registerShowTaskTool } from "./show-task.js";
 import { registerNextTaskTool } from "./next-task.js";
+import { registerExpandTaskTool } from "./expand-task.js";
 
 /**
  * Register all Task Master tools with the MCP server
@@ -28,6 +29,7 @@ export function registerTaskMasterTools(server) {
   registerGenerateTool(server);
   registerShowTaskTool(server);
   registerNextTaskTool(server);
+  registerExpandTaskTool(server);
 }
 
 export default {