This is a quickstart template to easily build and deploy a custom remote MCP server to the cloud using Azure functions. You can clone/restore/run on your local machine with debugging, and azd up to have it in the cloud in a couple minutes. The MCP server is secured by design using keys and HTTPs, and allows more options for OAuth using EasyAuth and/or API Management as well as network isolation using VNET.

Watch the video overview

If you're looking for this sample in more languages check out the Node.js/TypeScript and Python samples.

• .NET 8 SDK
• Azure Functions Core Tools >= 4.0.7030
• Azure Developer CLI
• To use Visual Studio to run and debug locally:
  • Visual Studio 2022.
  • Make sure to select the Azure development workload during installation.
• To use Visual Studio Code to run and debug locally:
  • Visual Studio Code
  • Azure Functions extension

Below is the architecture diagram for the Remote MCP Server using Azure Functions:

An Azure Storage Emulator is needed for this particular sample because we will save and get snippets from blob storage.

1. Start Azurite

   docker run -p 10000:10000 -p 10001:10001 -p 10002:10002 \
       mcr.microsoft.com/azure-storage/azurite

Note if you use Azurite coming from VS Code extension you need to run Azurite: Start now or you will see errors.

1. From the src folder, run this command to start the Functions host locally:

   cd src
   func start

Note by default this will use the webhooks route: /runtime/webhooks/mcp/sse. Later we will use this in Azure to set the key on client/host calls: /runtime/webhooks/mcp/sse?code=<system_key>

1. Add MCP Server from command palette and add URL to your running Function app's SSE endpoint:

   http://0.0.0.0:7071/runtime/webhooks/mcp/sse

2. List MCP Servers from command palette and start the server

3. In Copilot chat agent mode enter a prompt to trigger the tool, e.g., select some code and enter this prompt

   Say Hello 
   

   Save this snippet as snippet1 
   

   Retrieve snippet1 and apply to NewFile.cs
   

4. When prompted to run the tool, consent by clicking Continue

5. When you're done, press Ctrl+C in the terminal window to stop the func.exe host process.

1. In a new terminal window, install and run MCP Inspector

   npx @modelcontextprotocol/inspector node build/index.js

2. CTRL click to load the MCP Inspector web app from the URL displayed by the app (e.g. http://0.0.0.0:5173/#resources)

3. Set the transport type to SSE

4. Set the URL to your running Function app's SSE endpoint and Connect:

   http://0.0.0.0:7071/runtime/webhooks/mcp/sse

5. List Tools. Click on a tool and Run Tool.

Run this azd command to provision the function app, with any required Azure resources, and deploy your code:

azd up

You can opt-in to a VNet being used in the sample. To do so, do this before azd up

azd env set VNET_ENABLED true

Additionally, API Management can be used for improved security and policies over your MCP Server, and App Service built-in authentication can be used to set up your favorite OAuth provider including Entra.

Your client will need a key in order to invoke the new hosted SSE endpoint, which will be of the form https://<funcappname>.azurewebsites.net/runtime/webhooks/mcp/sse. The hosted function requires a system key by default which can be obtained from the portal or the CLI (az functionapp keys list --resource-group <resource_group> --name <function_app_name>). Obtain the system key named mcp_extension.

For MCP Inspector, you can include the key in the URL:

https://<funcappname>.azurewebsites.net/runtime/webhooks/mcp/sse?code=<your-mcp-extension-system-key>

For GitHub Copilot within VS Code, you should instead set the key as the x-functions-key header in mcp.json, and you would just use https://<funcappname>.azurewebsites.net/runtime/webhooks/mcp/sse for the URL. The following example uses an input and will prompt you to provide the key when you start the server from VS Code. Note mcp.json has already been included in this repo and will be picked up by VS Code. Click Start on the server to be prompted for values including functionapp-name (in your /.azure/*/.env file) and functions-mcp-extension-system-key which can be obtained from CLI command above or API Keys in the portal for the Function App.

{
    "inputs": [
        {
            "type": "promptString",
            "id": "functions-mcp-extension-system-key",
            "description": "Azure Functions MCP Extension System Key",
            "password": true
        },
        {
            "type": "promptString",
            "id": "functionapp-name",
            "description": "Azure Functions App Name"
        }
    ],
    "servers": {
        "remote-mcp-function": {
            "type": "sse",
            "url": "https://${input:functionapp-name}.azurewebsites.net/runtime/webhooks/mcp/sse",
            "headers": {
                "x-functions-key": "${input:functions-mcp-extension-system-key}"
            }
        },
        "local-mcp-function": {
            "type": "sse",
            "url": "http://0.0.0.0:7071/runtime/webhooks/mcp/sse"
        }
    }
}

Click Start on the server to be prompted for values including functionapp-name (in your /.azure/*/.env file) and functions-mcp-extension-system-key which can be obtained from CLI command above or API Keys in the portal for the Function App.

You can run the azd up command as many times as you need to both provision your Azure resources and deploy code updates to your function app.

When you're done working with your function app and related resources, you can use this command to delete the function app and its related resources from Azure and avoid incurring any further costs:

azd down

The function code for the GetSnippet and SaveSnippet endpoints are defined in SnippetsTool.cs. The McpToolsTrigger attribute applied to the async Run method exposes the code function as an MCP Server.

This shows the code for a few MCP server examples (get string, get object, save object):

[Function(nameof(SayHello))]
public string SayHello(
    [McpToolTrigger(HelloToolName, HelloToolDescription)] ToolInvocationContext context
)
{
    logger.LogInformation("Saying hello");
    return "Hello I am MCP Tool!";
}

[Function(nameof(GetSnippet))]
public object GetSnippet(
    [McpToolTrigger(GetSnippetToolName, GetSnippetToolDescription)] ToolInvocationContext context,
    [BlobInput(BlobPath)] string snippetContent)
{
    return snippetContent;
}

[Function(nameof(SaveSnippet))]
[BlobOutput(BlobPath)]
public string SaveSnippet(
    [McpToolTrigger(SaveSnippetToolName, SaveSnippetToolDescription)] ToolInvocationContext context,
    [McpToolProperty(SnippetNamePropertyName, PropertyType, SnippetNamePropertyDescription)] string name,
    [McpToolProperty(SnippetPropertyName, PropertyType, SnippetPropertyDescription)] string snippet)
{
    return snippet;
}

• Add API Management to your MCP server
• Add EasyAuth to your MCP server
• Enable VNET using VNET_ENABLED=true flag
• Learn more about related MCP efforts from Microsoft