Improve MCP Extension Support (#224)

* add mcptooltrigger annotation

* build

* update with java docs

* update version name to 3.1.1-alpha

* register McpToolTrigger in build tool so custom binding is not needed

* Add McpToolProperty annotation

* update mcp annotations

* update docs

* update library version

* revert mvnBuild.bat changes

* remove propertyName attribute since it will be filled by build tool

* add missing dataType method for McpToolTrigger

* fix some styling bugs

Author: ahmedmuhsin

pom.xml

@@ -4,7 +4,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>com.microsoft.azure.functions</groupId>
 	<artifactId>azure-functions-java-library</artifactId>
-	<version>3.1.0</version>
+	<version>3.2.0</version>
 	<packaging>jar</packaging>
 	<parent>
 		<groupId>com.microsoft.maven</groupId>

src/main/java/com/microsoft/azure/functions/annotation/McpToolProperty.java

@@ -0,0 +1,72 @@
+/**
+ * Copyright (c) Microsoft Corporation. All rights reserved.
+ * Licensed under the MIT License. See License.txt in the project root for
+ * license information.
+ */
+
+package com.microsoft.azure.functions.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Defines a strongly-typed input property for an MCP tool function parameter.
+ * <p>
+ * Alternative to using JSON format in {@link McpToolTrigger#toolProperties()}.
+ * Each annotated parameter receives a specific value from the tool invocation arguments.
+ * </p>
+ * 
+ * <p>Example:</p>
+ * <pre>
+ * {@literal @}FunctionName("searchFiles")
+ * public HttpResponseMessage search(
+ *     {@literal @}McpToolTrigger(name = "context", description = "Search files") String context,
+ *     {@literal @}McpToolProperty(
+ *         name = "query",
+ *         propertyName = "searchTerm",
+ *         propertyType = "string",
+ *         description = "Search term",
+ *         required = true
+ *     ) String searchTerm
+ * ) {
+ *     // Use searchTerm directly
+ * }
+ * </pre>
+ * 
+ * @see McpToolTrigger
+ * @since 3.2.0
+ */
+@Target({ElementType.PARAMETER})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface McpToolProperty {
+
+    /**
+     * The parameter binding name for the Azure Functions runtime.
+     * 
+     * @return The parameter binding name
+     */
+    String name();
+
+    /**
+     * The expected data type (e.g., "string", "number", "boolean", "array", "object").
+     * 
+     * @return The property type identifier
+     */
+    String propertyType();
+
+    /**
+     * Description of the property's purpose and usage.
+     * 
+     * @return Description of the property
+     */
+    String description();
+
+    /**
+     * Whether this property is required for tool execution.
+     * 
+     * @return true if required, false if optional
+     */
+    boolean required() default false;
+}

src/main/java/com/microsoft/azure/functions/annotation/McpToolTrigger.java

@@ -0,0 +1,84 @@
+/**
+ * Copyright (c) Microsoft Corporation. All rights reserved.
+ * Licensed under the MIT License. See License.txt in the project root for
+ * license information.
+ */
+
+package com.microsoft.azure.functions.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Triggers an Azure Function when invoked by the Model Context Protocol (MCP) tool system.
+ * <p>
+ * This annotation enables Azure Functions to be called as tools from MCP-compatible clients
+ * like AI assistants. The annotated parameter receives tool invocation arguments and context.
+ * </p>
+ * 
+ * <p>Example:</p>
+ * <pre>
+ * {@literal @}FunctionName("getFileContent")
+ * public HttpResponseMessage getFile(
+ *     {@literal @}McpToolTrigger(
+ *         name = "request",
+ *         description = "Reads file content",
+ *         toolProperties = "[{\"propertyName\":\"filePath\",\"propertyType\":\"string\"," +
+ *                         "\"description\":\"File path to read\"}]"
+ *     ) String toolRequest
+ * ) {
+ *     // Parse and handle tool request
+ * }
+ * </pre>
+ * 
+ * @see McpToolProperty
+ * @since 3.2.0
+ */
+@Target({ElementType.PARAMETER})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface McpToolTrigger {
+
+    /**
+     * The binding name for the tool invocation context parameter.
+     * 
+     * @return The parameter binding name
+     */
+    String name();
+
+    /**
+     * Defines how Functions runtime should treat the parameter value. Possible values are:
+     * <ul>
+     * <li>"": get the value as a string, and try to deserialize to actual parameter type like POJO</li>
+     * <li>string: always get the value as a string</li>
+     * <li>binary: get the value as a binary data, and try to deserialize to actual parameter type byte[]</li>
+     * </ul>
+     * 
+     * @return The dataType which will be used by the Functions runtime.
+     */
+    String dataType() default "";
+
+    /**
+     * Human-readable description of what this tool does.
+     * 
+     * @return Description of the tool's functionality
+     */
+    String description();
+
+    /**
+     * JSON array defining expected tool properties.
+     * <p>
+     * Each property should be a JSON object with: propertyName, propertyType, description.
+     * Alternative: use {@link McpToolProperty} annotations on parameters.
+     * </p>
+     * 
+     * <p>Example:</p>
+     * <pre>
+     * [{"propertyName":"fileName","propertyType":"string","description":"File to read"}]
+     * </pre>
+     * 
+     * @return JSON array of property definitions, or empty string
+     */
+    String toolProperties() default "";
+}