Add MCP Resource Trigger Support

package.json

@@ -1,6 +1,6 @@
 {
     "name": "@azure/functions",
-    "version": "4.11.2",
+    "version": "4.12.0",
     "description": "Microsoft Azure Functions NodeJS Framework",
     "keywords": [
         "azure",

src/app.ts

@@ -11,6 +11,7 @@ import {
     HttpHandler,
     HttpMethod,
     HttpMethodFunctionOptions,
+    McpResourceFunctionOptions,
     McpToolFunctionOptions,
     MySqlFunctionOptions,
     ServiceBusQueueFunctionOptions,
@@ -157,6 +158,17 @@ export function mcpTool(name: string, options: McpToolFunctionOptions): void {
     generic(name, convertToGenericOptions(options, trigger.mcpTool));
 }
 
+/**
+ * Registers an MCP Resource function in your app.
+ * This function is triggered when an MCP client reads the resource and allows you to define the resource content.
+ *
+ * @param name - The name of the function. This must be unique within your app and is primarily used for tracking purposes.
+ * @param options - Configuration options for the MCP Resource function, including the handler and trigger-specific settings.
+ */
+export function mcpResource(name: string, options: McpResourceFunctionOptions): void {
+    generic(name, convertToGenericOptions(options, trigger.mcpResource));
+}
+
 export function generic(name: string, options: GenericFunctionOptions): void {
     if (!hasSetModel) {
         setProgrammingModel();

src/constants.ts

@@ -1,6 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT License.
 
-export const version = '4.11.2';
+export const version = '4.12.0';
 
 export const returnBindingKey = '$return';

src/converters/toMcpResourceTriggerOptionsToRpc.ts

@@ -0,0 +1,60 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License.
+
+import { McpResourceTriggerOptions } from '../../types';
+
+/**
+ * Validates and returns an McpResourceTriggerOptions object.
+ *
+ * @param options - The input options to validate.
+ * @returns The validated McpResourceTriggerOptions object.
+ * @throws Error if required properties are missing or invalid.
+ */
+export function convertToMcpResourceTriggerOptionsToRpc(options: McpResourceTriggerOptions): McpResourceTriggerOptions {
+    // Validate required properties
+    if (!options.uri || typeof options.uri !== 'string' || options.uri.trim() === '') {
+        throw new Error('MCP Resource trigger requires a valid "uri" property.');
+    }
+
+    if (!options.resourceName || typeof options.resourceName !== 'string' || options.resourceName.trim() === '') {
+        throw new Error('MCP Resource trigger requires a valid "resourceName" property.');
+    }
+
+    // Build the result object with required properties
+    const result: McpResourceTriggerOptions = {
+        uri: options.uri,
+        resourceName: options.resourceName,
+    };
+
+    // Add optional properties if they are defined
+    if (options.title !== undefined) {
+        result.title = options.title;
+    }
+
+    if (options.description !== undefined) {
+        result.description = options.description;
+    }
+
+    if (options.mimeType !== undefined) {
+        result.mimeType = options.mimeType;
+    }
+
+    if (options.size !== undefined) {
+        if (typeof options.size !== 'number' || options.size < 0) {
+            throw new Error('MCP Resource trigger "size" must be a non-negative number.');
+        }
+        result.size = options.size;
+    }
+
+    if (options.metadata !== undefined && typeof options.metadata === 'string' && options.metadata.trim() !== '') {
+        // Validate that metadata is a valid JSON string
+        try {
+            JSON.parse(options.metadata);
+        } catch (e) {
+            throw new Error('MCP Resource trigger "metadata" must be a valid JSON string.');
+        }
+        result.metadata = options.metadata;
+    }
+
+    return result;
+}

src/converters/toMcpToolTriggerOptionsToRpc.ts

@@ -16,10 +16,26 @@ import { normalizeToolProperties } from '../utils/toolProperties';
 export function converToMcpToolTriggerOptionsToRpc(
     mcpToolTriggerOptions: McpToolTriggerOptions
 ): McpToolTriggerOptionsToRpc {
-    // Base object for the return value
+    // Validate metadata if provided - skip empty/whitespace strings
+    let validatedMetadata: string | undefined;
+    if (
+        mcpToolTriggerOptions.metadata !== undefined &&
+        typeof mcpToolTriggerOptions.metadata === 'string' &&
+        mcpToolTriggerOptions.metadata.trim() !== ''
+    ) {
+        try {
+            JSON.parse(mcpToolTriggerOptions.metadata);
+            validatedMetadata = mcpToolTriggerOptions.metadata;
+        } catch (e) {
+            throw new Error('MCP Tool trigger "metadata" must be a valid JSON string.');
+        }
+    }
+
+    // Base object for the return value - metadata is independent of toolProperties
     const baseResult = {
         toolName: mcpToolTriggerOptions.toolName,
         description: mcpToolTriggerOptions.description,
+        ...(validatedMetadata !== undefined && { metadata: validatedMetadata }),
     };
 
     // Try to normalize tool properties first (handles both array and fluent formats)

src/trigger.ts

@@ -12,6 +12,8 @@ import {
     GenericTriggerOptions,
     HttpTrigger,
     HttpTriggerOptions,
+    McpResourceTrigger,
+    McpResourceTriggerOptions,
     McpToolTrigger,
     McpToolTriggerOptions,
     MySqlTrigger,
@@ -34,6 +36,7 @@ import {
     WebPubSubTriggerOptions,
 } from '@azure/functions';
 import { addBindingName } from './addBindingName';
+import { convertToMcpResourceTriggerOptionsToRpc } from './converters/toMcpResourceTriggerOptionsToRpc';
 import { converToMcpToolTriggerOptionsToRpc } from './converters/toMcpToolTriggerOptionsToRpc';
 
 export function http(options: HttpTriggerOptions): HttpTrigger {
@@ -143,6 +146,21 @@ export function mcpTool(options: McpToolTriggerOptions): McpToolTrigger {
     });
 }
 
+/**
+ * Creates an MCP Resource trigger configuration.
+ * This function is used to define an MCP Resource trigger for an Azure Function.
+ * MCP Resources are read-only data sources that can be accessed by MCP clients.
+ *
+ * @param options - The configuration options for the MCP Resource trigger, including resource-specific metadata.
+ * @returns An MCP Resource trigger object with the specified configuration.
+ */
+export function mcpResource(options: McpResourceTriggerOptions): McpResourceTrigger {
+    return addTriggerBindingName({
+        ...convertToMcpResourceTriggerOptionsToRpc(options),
+        type: 'mcpResourceTrigger',
+    });
+}
+
 export function generic(options: GenericTriggerOptions): FunctionTrigger {
     return addTriggerBindingName(options);
 }