Add IoT Hub device list command

.github/CODEOWNERS

@@ -120,6 +120,12 @@
 # ServiceLabel: %tools-Grafana
 # ServiceOwners:                       @weng5e @xiangyan99
 
+# PRLabel: %tools-IoTHub
+/tools/Azure.Mcp.Tools.IoTHub/         @prerakpradhan @jichang1 @microsoft/azure-mcp
+
+# ServiceLabel: %tools-IoTHub
+# ServiceOwners:                       @prerakpradhan @jichang1 @microsoft/azure-mcp
+
 # PRLabel: %tools-KeyVault
 /tools/Azure.Mcp.Tools.KeyVault/       @vcolin7 @JonathanCrd @microsoft/azure-mcp
 

.vscode/mcp.json

@@ -0,0 +1,16 @@
+{
+  "servers": {
+    "iris-local-mcp": {
+      "type": "stdio",
+      "command": "dotnet",
+      "args": [
+        "servers/Azure.Mcp.Server/src/bin/Release/net9.0/azmcp.dll",
+        "server",
+        "start",
+        "--namespace",
+        "iothub"
+      ]
+    }
+  },
+  "inputs": []
+}

.vscode/settings.json

@@ -0,0 +1,7 @@
+{
+    "chat.mcp.serverSampling": {
+        "mcp-pr/.vscode/mcp.json: iris-local-mcp": {
+            "allowedDuringChat": true
+        }
+    }
+}

Directory.Packages.props

@@ -30,6 +30,7 @@
     <PackageVersion Include="Azure.ResourceManager.ContainerService" Version="1.2.5" />
     <PackageVersion Include="Azure.ResourceManager.EventGrid" Version="1.2.0-beta.2" />
     <PackageVersion Include="Azure.ResourceManager.EventHubs" Version="1.2.1" />
+    <PackageVersion Include="Azure.ResourceManager.IotHub" Version="1.2.0-beta.2" />
     <PackageVersion Include="Azure.ResourceManager.CognitiveServices" Version="1.5.1" />
     <PackageVersion Include="Microsoft.CognitiveServices.Speech" Version="1.46.0" />
     <PackageVersion Include="Azure.ResourceManager.MySql" Version="1.1.2" />
@@ -86,7 +87,7 @@
     <PackageVersion Include="System.Net.ServerSentEvents" Version="10.0.0-rc.1.25451.107" />
     <PackageVersion Include="System.Numerics.Tensors" Version="9.0.0" />
     <PackageVersion Include="System.Text.Json" Version="9.0.9" />
-    <PackageVersion Include="OpenTelemetry.Exporter.OpenTelemetryProtocol" Version="1.12.0" />
+    <PackageVersion Include="OpenTelemetry.Exporter.OpenTelemetryProtocol" Version="1.15.3" />
     <PackageVersion Include="Azure.Monitor.OpenTelemetry.AspNetCore" Version="1.3.0" />
     <PackageVersion Include="Microsoft.Extensions.Azure" Version="1.11.0" />
     <PackageVersion Include="Microsoft.AspNetCore.SignalR.Client" Version="9.0.9" />

core/Azure.Mcp.Core/src/Areas/Server/Resources/consolidated-tools.json

@@ -947,6 +947,39 @@
         "keyvault_secret_create"
       ]
     },
+    {
+      "name": "query_azure_iothub_devices",
+      "description": "List devices and retrieve device identity metadata from the Azure IoT Hub device registry.",
+      "toolMetadata": {
+        "destructive": {
+          "value": false,
+          "description": "This tool performs only read operations without deleting or modifying existing resources."
+        },
+        "idempotent": {
+          "value": true,
+          "description": "Running this operation multiple times with the same arguments produces the same result without additional effects."
+        },
+        "openWorld": {
+          "value": false,
+          "description": "This tool's domain of interaction is closed and well-defined, limited to a specific set of entities."
+        },
+        "readOnly": {
+          "value": true,
+          "description": "This tool only performs read operations without modifying any state or data."
+        },
+        "secret": {
+          "value": false,
+          "description": "This tool does not handle sensitive or secret information."
+        },
+        "localRequired": {
+          "value": false,
+          "description": "This tool is available in both local and remote server modes."
+        }
+      },
+      "mappedToolList": [
+        "iothub_device_list"
+      ]
+    },
     {
       "name": "import_azure_key_vault_certificates",
       "description": "Import external certificates into Azure Key Vault",

core/Azure.Mcp.Core/src/Services/Http/HttpClientService.cs

@@ -70,11 +70,11 @@ private HttpClient CreateClientInternal()
 #if DEBUG
         // If a TEST_PROXY_URL is configured, insert RecordingRedirectHandler as the last delegating handler
         var testProxyUrl = Environment.GetEnvironmentVariable("TEST_PROXY_URL");
-        Console.WriteLine("Using test proxy URL: " + testProxyUrl);
         HttpMessageHandler pipeline = handler;
         if (!string.IsNullOrWhiteSpace(testProxyUrl) && Uri.TryCreate(testProxyUrl, UriKind.Absolute, out var proxyUri))
         {
-            Console.WriteLine("Inserting RecordingRedirectHandler for test proxy.");
+            // Write to stderr so stdout stays reserved for command/JSON-RPC output.
+            Console.Error.WriteLine("Inserting RecordingRedirectHandler for test proxy: " + testProxyUrl);
             // RecordingRedirectHandler should be the last delegating handler before the transport
             pipeline = new RecordingRedirectHandler(proxyUri)
             {

dotnet-tools.json

@@ -0,0 +1,13 @@
+{
+  "version": 1,
+  "isRoot": true,
+  "tools": {
+    "azure.mcp": {
+      "version": "2.0.4",
+      "commands": [
+        "azmcp"
+      ],
+      "rollForward": false
+    }
+  }
+}

package.json

@@ -0,0 +1,5 @@
+{
+  "dependencies": {
+    "@azure/mcp": "^3.0.0-beta.19"
+  }
+}

servers/Azure.Mcp.Server/CHANGELOG.md

@@ -6,6 +6,8 @@ The Azure MCP Server updates automatically by default whenever a new release com
 
 ### Features Added
 
+- Added `azmcp iothub device list` to list device identities in an Azure IoT Hub device registry. The command returns device metadata without authentication keys, applies a default page size of 100 and a maximum of 100 to `--max-count`, returns a validation error when `--max-count` is less than 1, and flags `truncated` (with an explanatory message) when the hub contains more devices than were returned.
+
 ### Breaking Changes
 
 ### Bugs Fixed

servers/Azure.Mcp.Server/README.md

@@ -554,6 +554,7 @@ The Azure MCP Server provides tools for interacting with **40+ Azure service are
 - 🐘 **Azure Database for PostgreSQL** - PostgreSQL database management
 - 📊 **Azure Event Grid** - Event routing and management
 - ⚡ **Azure Functions** - Function App management
+- 🌐 **Azure IoT Hub** - IoT device management and messaging
 - 🔑 **Azure Key Vault** - Secrets, keys, and certificates
 - ☸️ **Azure Kubernetes Service (AKS)** - Container orchestration
 - 📦 **Azure Load Testing** - Performance testing

servers/Azure.Mcp.Server/docs/azmcp-commands.md

@@ -1240,6 +1240,20 @@ azmcp loadtesting testrun update --subscription <subscription> \
 # ❌ Destructive | ✅ Idempotent | ❌ OpenWorld | ✅ ReadOnly | ❌ Secret | ❌ LocalRequired
 azmcp grafana list --subscription <subscription>
 ```
+### Azure IoT Hub Operations
+
+#### Device Registry Operations
+
+```bash
+# List devices in an IoT Hub
+# Returns one page of device identities. --max-count sets the page size (default 100, maximum 100).
+# When the hub has more devices than were returned, the response sets truncated=true with an explanatory message.
+# ❌ Destructive | ✅ Idempotent | ❌ OpenWorld | ✅ ReadOnly | ❌ Secret | ❌ LocalRequired
+azmcp iothub device list --subscription <subscription> \
+                         --resource-group <resource-group> \
+                         --name <iothub-name> \
+                         [--max-count <max-count>]
+```
 
 ### Azure Marketplace Operations
 

servers/Azure.Mcp.Server/docs/e2eTestPrompts.md

@@ -304,6 +304,15 @@ This file contains prompts used for end-to-end testing to ensure each tool is in
 | functionapp_get | Show me my Azure function apps |
 | functionapp_get | What function apps do I have? |
 
+## Azure IoT Hub
+
+| Tool Name | Test Prompt |
+|:----------|:----------|
+| iothub_device_list | List all devices in IoT Hub <iothub-name> |
+| iothub_device_list | Show me the devices in IoT Hub <iothub-name> in resource group <resource-group> |
+| iothub_device_list | List the first 10 devices in IoT Hub <iothub-name> |
+| iothub_device_list | What devices are registered in IoT Hub <iothub-name>? |
+
 ## Azure Key Vault
 
 | Tool Name | Test Prompt |

servers/Azure.Mcp.Server/src/Program.cs

@@ -34,7 +34,9 @@ private static async Task<int> Main(string[] args)
             services.AddLogging(builder =>
             {
                 builder.ConfigureOpenTelemetryLogger();
-                builder.AddConsole();
+                // Send console logs to stderr so stdout carries only the command's JSON
+                // response. Keeps CLI output parseable and avoids corrupting stdio MCP output.
+                builder.AddConsole(options => options.LogToStandardErrorThreshold = LogLevel.Trace);
                 builder.SetMinimumLevel(LogLevel.Information);
             });
 
@@ -97,6 +99,7 @@ private static IAreaSetup[] RegisterAreas()
             new Azure.Mcp.Tools.Foundry.FoundrySetup(),
             new Azure.Mcp.Tools.FunctionApp.FunctionAppSetup(),
             new Azure.Mcp.Tools.Grafana.GrafanaSetup(),
+            new Azure.Mcp.Tools.IoTHub.IoTHubSetup(),
             new Azure.Mcp.Tools.KeyVault.KeyVaultSetup(),
             new Azure.Mcp.Tools.Kusto.KustoSetup(),
             new Azure.Mcp.Tools.LoadTesting.LoadTestingSetup(),

tools/Azure.Mcp.Tools.IoTHub/src/AssemblyInfo.cs

@@ -0,0 +1,7 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("Azure.Mcp.Tools.IoTHub.UnitTests")]
+[assembly: InternalsVisibleTo("Azure.Mcp.Tools.IoTHub.LiveTests")]

tools/Azure.Mcp.Tools.IoTHub/src/Azure.Mcp.Tools.IoTHub.csproj

@@ -0,0 +1,20 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <IsAotCompatible>true</IsAotCompatible>
+  </PropertyGroup>
+  <ItemGroup>
+    <EmbeddedResource Include="**\Resources\*.txt" />
+    <EmbeddedResource Include="**\Resources\*.json" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\core\Azure.Mcp.Core\src\Azure.Mcp.Core.csproj" />
+  </ItemGroup>
+  <ItemGroup />
+  <ItemGroup>
+    <PackageReference Include="Azure.ResourceManager" />
+    <PackageReference Include="Azure.ResourceManager.IotHub" />
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection" />
+    <PackageReference Include="ModelContextProtocol" />
+    <PackageReference Include="System.CommandLine" />
+  </ItemGroup>
+</Project>