Function Runtime Version 4.83 doesn't include Microsoft.Azure.Functions.Extensions.Mcp class.

[komayama]

Hi Team,

I'm happy to publish MCP server on Azure Functions. I tried to be running MCP Server the bellow Python and TypeScripts on runtime host version 4.83. https://github.com/Azure-Samples/remote-mcp-functions-python https://github.com/Azure-Samples/remote-mcp-functions-typescript

Looks like this host runtime doesn't have Microsoft.Azure.Functions.Extensions.Mcp extension bundle even set ExtensionBundleExperimental version.

https://github.com/Azure/azure-functions-extension-bundles/releases

host.json

{
  "version": "2.0",
  "logging": {
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": true,
        "excludedTypes": "Request"
      }
    }
  },
  "extensionBundle": {
    "id": "Microsoft.Azure.Functions.ExtensionBundle.Experimental",
    "version": "[4.*, 5.0.0)"
  }
}

$ func start

Azure Functions Core Tools
Core Tools Version:       4.0.5907 Commit hash: N/A +807e89766a92b14fd07b9f0bc2bea1d8777ab209 (64-bit)
Function Runtime Version: 4.834.3.22875

[2025-04-16T06:54:42.297Z] Error configuring services in an external startup class.
[2025-04-16T06:54:42.298Z] Error configuring services in an external startup class. Microsoft.Azure.Functions.Extensions.Mcp: Could not load file or assembly 'System.Threading.Channels, Version=8.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'. The system cannot find the file specified.
[2025-04-16T06:54:42.298Z] .
[2025-04-16T06:54:42.343Z] A host error has occurred during startup operation '42fd56d8-9df4-48fe-92a8-17d10ffbccff'.
[2025-04-16T06:54:42.343Z] Microsoft.Azure.WebJobs.Script: Error configuring services in an external startup class. Microsoft.Azure.Functions.Extensions.Mcp: Could not load file or assembly 'System.Threading.Channels, Version=8.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'. The system cannot find the file specified.
[2025-04-16T06:54:42.343Z] .
Value cannot be null. (Parameter 'provider')
[2025-04-16T06:54:42.357Z] Host startup operation has been canceled
[2025-04-16T06:55:09.900Z] Unable to get table reference or create table. Aborting write operation.
[2025-04-16T06:55:09.900Z] Microsoft.Azure.Cosmos.Table: Connection refused (127.0.0.1:10002). System.Net.Http: Connection refused (127.0.0.1:10002). System.Net.Sockets: Connection refused.

[komayama]

I had switched Runtime Version 4.1037 is successfully running Function Host.

$ func start

Azure Functions Core Tools
Core Tools Version:       4.0.7030 Commit hash: N/A +bb4c949899cd5659d6bfe8b92cc923453a2e8f88 (64-bit)
Function Runtime Version: 4.1037.0.23568

[2025-04-16T07:16:12.620Z] MCP server SSE endpoint: http://localhost:7071/runtime/webhooks/mcp/sse
[2025-04-16T07:16:12.684Z] result {
[2025-04-16T07:16:12.684Z]   toolName: 'mcpToolTriggerWithZod',
[2025-04-16T07:16:12.684Z]   description: 'Mcp Tool with Zod Validation Example',
[2025-04-16T07:16:12.684Z]   toolProperties: '[{"propertyName":"latitude","propertyType":"number","description":"Latitude of the location"},{"propertyName":"longitude","propertyType":"array","description":"Longitude of the location"}]'
[2025-04-16T07:16:12.685Z] }
[2025-04-16T07:16:12.685Z] result {
[2025-04-16T07:16:12.685Z]   toolName: 'mcpToolTriggerWithZodObject',
[2025-04-16T07:16:12.685Z]   description: 'Mcp Tool with Zod Validation Example',
[2025-04-16T07:16:12.685Z]   toolProperties: '[{"propertyName":"latitude","propertyType":"number","description":"Latitude of the location"},{"propertyName":"longitude","propertyType":"boolean","description":"Longitude of the location"}]'
[2025-04-16T07:16:12.685Z] }
[2025-04-16T07:16:12.745Z] Worker process started and initialized.

Functions:

        getSnippet: mcpToolTrigger

        hello: mcpToolTrigger

        mcpToolTriggerWithArguments: mcpToolTrigger

        mcpToolTriggerWithZod: mcpToolTrigger

        mcpToolTriggerWithZodObject: mcpToolTrigger

        saveSnippet: mcpToolTrigger

For detailed output, run func with --verbose flag.
[2025-04-16T07:16:14.475Z] Host did not shutdown within its allotted time.
[2025-04-16T07:16:14.479Z] Shutting down language worker channels for runtime:node
[2025-04-16T07:16:17.749Z] Host lock lease acquired by instance ID '0000000000000000000000006CA709AB'.

[manvkaur]

@komayama, The experimental extension bundle requires Azure Functions Core Tools version 4.0.7030 or higher. The exception you're encountering is due to a missing .NET 8 dependency, which is expected when using this bundle with an older version of Core Tools. This issue is resolved in Core Tools version >= 4.0.7030 or Host version >= 4.1037.

@paulyuk , please feel free to close this issue and let's update our documentation that experimental bundles require core tools 4.0.7030 as minimum

[komayama]

Hi @manvkaur, Thank you for the confirm my environment questions and more detail explain. I created PR which is helpful content minimum azure functions core tools version.