Add MCP prompt sample functions

- PromptExamples.java: 4 sample prompt functions demonstrating
  McpPromptTrigger and McpPromptArgument usage (code review,
  summarize, no-args, and inline-args prompts)
- local.settings.json: add staging CDN for extension bundle with
  prompt support

Author: ahmedmuhsin

samples/FunctionsMcpTool/local.settings.json

@@ -2,6 +2,7 @@
   "IsEncrypted": false,
   "Values": {
     "AzureWebJobsStorage": "UseDevelopmentStorage=true",
-    "FUNCTIONS_WORKER_RUNTIME": "java"
+    "FUNCTIONS_WORKER_RUNTIME": "java",
+    "FUNCTIONS_EXTENSIONBUNDLE_SOURCE_URI": "https://cdn-staging.functions.azure.com/public"
   }
 }

samples/FunctionsMcpTool/src/main/java/com/function/PromptExamples.java

@@ -0,0 +1,110 @@
+package com.function;
+
+import com.microsoft.azure.functions.ExecutionContext;
+import com.microsoft.azure.functions.annotation.FunctionName;
+import com.microsoft.azure.functions.annotation.McpPromptArgument;
+import com.microsoft.azure.functions.annotation.McpPromptTrigger;
+
+/**
+ * Demonstrates MCP Prompt functions that expose prompt templates to MCP clients.
+ * Clients discover prompts via prompts/list and invoke them via prompts/get.
+ * 
+ * Return a plain string (auto-wrapped into a single user message by the host)
+ * or a JSON-serialized GetPromptResult for multi-message / rich content responses.
+ */
+public class PromptExamples {
+
+    /**
+     * A code review prompt with multiple arguments (1 required, 1 optional).
+     * Uses McpPromptArgument annotations to define arguments in a strongly-typed way.
+     */
+    @FunctionName("CodeReviewPrompt")
+    public String codeReviewPrompt(
+            @McpPromptTrigger(
+                    name = "code_review",
+                    description = "Generates a code review prompt for the given code snippet",
+                    title = "Code Review")
+            String context,
+            @McpPromptArgument(
+                    name = "code",
+                    argumentName = "code",
+                    description = "The code to review",
+                    isRequired = true)
+            String code,
+            @McpPromptArgument(
+                    name = "language",
+                    argumentName = "language",
+                    description = "The programming language")
+            String language,
+            final ExecutionContext executionContext) {
+
+        executionContext.getLogger().info("Generating code review prompt");
+
+        String lang = (language != null && !language.isEmpty()) ? language : "unknown";
+        String snippet = (code != null && !code.isEmpty()) ? code : "// no code provided";
+
+        return "Please review the following " + lang + " code and suggest improvements:\n\n```"
+                + lang + "\n" + snippet + "\n```";
+    }
+
+    /**
+     * A summarize prompt with a single required argument and plain string return.
+     * The host auto-wraps the returned string into a PromptMessage with role "user".
+     */
+    @FunctionName("SummarizePrompt")
+    public String summarizePrompt(
+            @McpPromptTrigger(
+                    name = "summarize",
+                    description = "Summarizes the provided text",
+                    title = "Summarize Text")
+            String context,
+            @McpPromptArgument(
+                    name = "text",
+                    argumentName = "text",
+                    description = "The text to summarize",
+                    isRequired = true)
+            String text,
+            final ExecutionContext executionContext) {
+
+        executionContext.getLogger().info("Generating summarize prompt");
+
+        String input = (text != null && !text.isEmpty()) ? text : "No text provided";
+        return "Please provide a concise summary of the following text:\n\n" + input;
+    }
+
+    /**
+     * A prompt with no arguments. Tests the edge case of a prompt
+     * that takes no user input.
+     */
+    @FunctionName("NoArgsPrompt")
+    public String noArgsPrompt(
+            @McpPromptTrigger(
+                    name = "no_args_prompt",
+                    description = "A prompt that requires no arguments",
+                    title = "No Arguments Prompt")
+            String context,
+            final ExecutionContext executionContext) {
+
+        executionContext.getLogger().info("Generating no-args prompt");
+        return "This prompt requires no arguments. Please provide general guidance.";
+    }
+
+    /**
+     * A prompt with inline promptArguments JSON instead of McpPromptArgument annotations.
+     * This is the alternative approach — useful when arguments are static/known at compile time.
+     */
+    @FunctionName("InlineArgsPrompt")
+    public String inlineArgsPrompt(
+            @McpPromptTrigger(
+                    name = "inline_args_prompt",
+                    description = "A prompt with arguments defined via inline JSON",
+                    title = "Inline Arguments Prompt",
+                    promptArguments = "[{\"name\":\"topic\",\"description\":\"The topic to discuss\",\"required\":false},"
+                            + "{\"name\":\"style\",\"description\":\"The writing style\",\"required\":false}]")
+            String context,
+            final ExecutionContext executionContext) {
+
+        executionContext.getLogger().info("Generating inline-args prompt");
+        return "Please write about the specified topic in the requested style.";
+    }
+}