Add Azure MCP Tools

Add a New Tool to Azure MCP

Purpose

Step-by-step workflow for adding a new command to any Azure MCP toolset.

Each phase has an explicit gate — do not proceed until the gate passes.

Decision: New Toolset or Existing?

Before starting, determine:

• Adding to existing toolset? → Skip to Phase 1.
• Creating a new toolset? → Complete Phase 0 first.

⚠️ CRITICAL: Does your command interact with Azure resources?

| | Azure Service Commands | Non-Azure Commands |

|---|---|---|

| Examples | ACR Registry List, SQL Database List, Storage Account Get | CLI wrappers, Best Practices, Documentation tools |

| test-resources.bicep | ✅ Required | ❌ Skip |

| test-resources-post.ps1 | ✅ Required (even if basic) | ❌ Skip |

| RBAC role assignments | ✅ Required | ❌ Skip |

| Live tests | ✅ Required (recorded) | ❌ Skip |

| Unit tests | ✅ Required | ✅ Required |

Security Requirements

> Terminology note: In this repo, _tool_ refers to the MCP-exposed capability and _command_ refers to the underlying C# command class implementation. Both terms appear in the codebase and docs.

All tool inputs are untrusted. These requirements apply at every phase and are not optional.

Input Validation

• Validate inputs against the specific naming rules of the Azure resource being targeted (length, allowed characters, casing). Do not apply a generic blocklist — Azure resource naming rules vary significantly by service.
• Example: Storage account names are 3–24 lowercase alphanumeric characters only.
• Example: Resource group names allow letters, digits, underscores, hyphens, and periods up to 90 characters.
• Reference: Azure naming rules and restrictions
• Use ValidateOptions for semantic constraints beyond nullability (name length, format, mutual exclusivity, and allowed value sets). Only reject characters that are provably invalid for the specific resource type. This applies to both the new two-generic SubscriptionCommand pattern and the legacy one-generic pattern — see the ValidateOptions override guidance in Phase 1d.
• Prefer SDK/runtime validators and deterministic checks first (Length, explicit allowed-value sets, character/category checks).

Secure Logging

• Never log raw option objects ({@Options}) — they may contain secrets, connection strings, or PII.
• Log only individually named, known-safe parameters. For example: options.Subscription, options.ResourceGroup, Name.
• Do not include sensitive field values in error messages returned to callers.
• Strip or redact secret values before surfacing exception details.

// ✅ Log only known-safe, individually named fields
_logger.LogError(ex, "Error in {Operation}. Subscription: {Subscription}, ResourceGroup: {ResourceGroup}",
    Name, options.Subscription, options.ResourceGroup);

// ❌ Never log the whole options object — it may contain keys, connection strings, or PII
_logger.LogError(ex, "Error in {Operation}. Options: {@Options}", Name, options);

// ❌ Never surface raw exception bodies to callers — they may contain tokens or account metadata
return $"Request failed: {requestFailedException.Message}"; // may include auth headers

Safe Downstream Interactions

• Never concatenate user input directly without prior validation into URLs, shell commands, resource identifiers, query strings, etc.
• Use EndpointValidator from Microsoft.Mcp.Core.Helpers to guard all endpoint usage — choose the method that matches your scenario:
• Azure service data-plane endpoint (endpoint derived from a resource name, e.g. storage account, ACR, App Config): call EndpointValidator.ValidateAzureServiceEndpoint(endpoint, serviceType, TenantService.CloudConfiguration.ArmEnvironment) before constructing the client. This enforces the correct per-cloud domain suffix (e.g. .blob.core.windows.net / .blob.core.chinacloudapi.cn) and HTTPS.
• User-supplied URL to a known external service (e.g. a GitHub URL the user provides): call EndpointValidator.ValidateExternalUrl(url, allowedHosts) with an explicit allowlist of permitted hosts.
• User-supplied target URL with no known domain (e.g. a load-test target the user controls): call EndpointValidator.ValidatePublicTargetUrl(url), which enforces HTTPS/HTTP-only schemes, rejects private/reserved IP ranges, rejects reserved hostnames, and resolves DNS to catch hostnames that map to internal IPs.
• For services that *construct* the endpoint internally (not from user input), use the cloud-type switch pattern (see Phase 1c: Service Implementation) — EndpointValidator is not required in that case but ValidateAzureServiceEndpoint can be added as a defense-in-depth layer.
• Control-plane operations (ARM resource creation, RBAC assignments, policy etc.) do not need EndpointValidator because they go through the typed Azure SDK ARM client. Construct ARM resource IDs using ResourceIdentifier or collection helpers — never by string-interpolating subscription/resource-group/resource-name directly into a raw ARM path.
• For new commands and services, always pass CancellationToken as the final parameter to all async downstream calls and propagate it throughout — never substitute CancellationToken.None or default at call sites.
• Fail closed: if tenant, subscription, or resource context is ambiguous, return an explicit validation error and require the caller to specify the value. Do not silently pick a default.

MCP-Specific Threat Patterns

| Threat | Established mitigation in this project |

|--------|----------------------------------------|

| Input abuse (oversized/malformed names) | Override ValidateOptions with resource-specific length and format checks using deterministic validation first (length bounds, allowed-value sets, character/category checks). For query inputs, use a dedicated validator class — see CosmosQueryValidator.EnsureReadOnlySelect (tools/Azure.Mcp.Tools.Cosmos/src/Validation/CosmosQueryValidator.cs) as a reference for length cap, keyword blocking, and injection pattern detection. |

| Injection into downstream systems | For user-supplied queries: use a validator class that enforces a single read-only statement, caps length, strips/blocks dangerous tokens, and detects tautology patterns. Do not interpolate user input into query strings directly — prefer parameterized APIs where available. For blob/resource URIs: call EndpointValidator.ValidateAzureServiceEndpoint before constructing any client (see tools/Azure.Mcp.Tools.Compute/src/Services/ComputeService.cs blob URI handling as a reference). |

| Secret leakage via logs or error responses | Log only individually named, non-sensitive fields: options.Subscription, options.ResourceGroup, Name. Never use {@Options} or log connection strings, keys, or endpoint values. Override GetErrorMessage to return actionable but non-revealing messages — strip raw RequestFailedException bodies that may contain tokens or account metadata. |

| Cross-tenant/resource confusion | SubscriptionCommand base class enforces that --subscription is always present and resolved via ISubscriptionResolver before ExecuteAsync is called. Pass options.Tenant to all service calls so ITenantService can validate tenant context per-request. Fail explicitly if tenant context is ambiguous — do not fall back silently. |

| SSRF-like endpoint misuse | Use EndpointValidator from Microsoft.Mcp.Core.Helpers: ValidateAzureServiceEndpoint(endpoint, serviceType, armEnvironment) for Azure data-plane endpoints, ValidateExternalUrl(url, allowedHosts) for user-supplied URLs to known hosts, ValidatePublicTargetUrl(url) for arbitrary user-controlled targets (DNS-resolves and blocks private/reserved IPs). |

Using AI to Generate Tool Code

When using an AI assistant (such as GitHub Copilot) to scaffold or generate command, service, or test code, include the following in every prompt:

Requirements:
- Validate user-controlled inputs in `ValidateOptions` using resource-specific rules (naming rules, allowed values, length caps) where applicable; do not use one generic rule for all options.
- Prefer SDK/runtime validators and deterministic checks for user input validation.
- Log only individually named, known-safe parameters; never log option objects, credentials, keys, connection strings, or other secret-bearing fields.
- For endpoint/URL inputs, use `EndpointValidator` methods appropriate to the scenario (`ValidateAzureServiceEndpoint`, `ValidateExternalUrl`, or `ValidatePublicTargetUrl`). Avoid direct interpolation of unvalidated input into URLs or downstream queries.
- Add negative tests for relevant security cases introduced by the command (for example malformed names, invalid endpoint hosts, or unsafe query text) rather than a one-size-fits-all set of tests.
- Keep error messages actionable but non-revealing: avoid exposing stack traces, raw backend payloads, or sensitive values to callers.

Review every AI-generated snippet for these properties before committing. Generated code that omits them must be corrected before the security gate in Phase 7 can be met.

Phase 0: New Toolset Setup (skip if adding to existing toolset)

Create the toolset directory structure:

tools/Azure.Mcp.Tools.{Toolset}/
├── src/
│   ├── Azure.Mcp.Tools.{Toolset}.csproj
│   ├── {Toolset}Setup.cs
│   ├── Commands/
│   │   ├── {Resource}/
│   │   │   └── {Resource}{Operation}Command.cs
│   │   └── {Toolset}JsonContext.cs
│   ├── Options/
│   │   └── {Resource}/
│   │       └── {Resource}{Operation}Options.cs
│   ├── Services/
│   │   ├── I{Toolset}Service.cs
│   │   └── {Toolset}Service.cs
│   └── Models/
└── tests/
    ├── Azure.Mcp.Tools.{Toolset}.Tests/
    │   └── Azure.Mcp.Tools.{Toolset}.Tests.csproj
    ├── test-resources.bicep          (Azure service commands only)
    └── test-resources-post.ps1       (Azure service commands only)

Required setup steps:

• Add package version to Directory.Packages.props (if Azure SDK needed)
• Register the project in solution files by running:

pwsh eng/scripts/Update-Solutions.ps1 -All

• Register the new toolset in servers/Azure.Mcp.Server/src/Program.cs RegisterAreas() (alphabetical order)
• Choose the appropriate base class:
• Commands that need an Azure subscription (most Azure service tools) → inherit from SubscriptionCommand<TOptions, TResult> and inject ISubscriptionResolver.
• Commands that do NOT need a subscription (CLI wrappers, documentation tools, best-practice advisors) → inherit from BaseCommand<TOptions, TResult> directly.

Only add a shared intermediate base command if you have real cross-command logic shared by multiple commands in the same toolset.

• Register both the service and the command as singletons in {Toolset}Setup.cs ConfigureServices:

   public void ConfigureServices(IServiceCollection services)
   {
       services.AddSingleton<I{Toolset}Service, {Toolset}Service>();
       services.AddSingleton<{Resource}{Operation}Command>();
   }

GATE: dotnet build servers/Azure.Mcp.Server/src must pass.

Phase 1: Implement Command

Create these files in order:

1a. Options Class (with [Option] attributes)

File: src/Options/{Resource}/{Resource}{Operation}Options.cs

using Azure.Mcp.Core.Options;
using Microsoft.Mcp.Core.Models;
using Microsoft.Mcp.Core.Options;

namespace Azure.Mcp.Tools.{Toolset}.Options.{Resource};

public class {Resource}{Operation}Options : ISubscriptionOption
{
    [Option("Description of what this option does (e.g., 'The name of the resource').")]
    public string? MyOption { get; set; }

    [Option(OptionDescriptions.ResourceGroup)]
    public string? ResourceGroup { get; set; }

    [Option(OptionDescriptions.Subscription)]
    public string? Subscription { get; set; }

    [Option(OptionDescriptions.Tenant)]
    public string? Tenant { get; set; }

    [Option(Name = "retry")]
    public RetryPolicyOptions? RetryPolicy { get; set; }
}

Rules:

• Implement ISubscriptionOption for commands that need subscription resolution
• Use [Option("description")] for the description — property name auto-converts to --kebab-case
• Use [Option(Name = "custom")] only when the default kebab-case conversion is wrong (e.g., RetryPolicy → --retry not --retry-policy)
• Use [Option(OptionDescriptions.X)] for shared descriptions (Subscription, Tenant, ResourceGroup, AuthMethod)
• Use subscription (never subscriptionId) — supports both IDs and names
• Use resourceGroup (never resourceGroupName)
• Use singular nouns for resources (server not serverName)
• Remove unnecessary name suffixes (Account / --account not AccountName / --account-name)
• Use required on required options; use nullable types (?) for optional options.
• Non-nullable value types (e.g., public int Count { get; set; }) are always valid without required — they default to 0. Use required if the caller must explicitly provide a value, or use int? if the parameter should be truly optional.
• Order: command-specific options first, then ResourceGroup, Subscription, Tenant, AuthMethod, RetryPolicy
• Keep parameter names consistent with Azure SDK parameters when possible

> Note: Options are defined entirely via [Option] attributes.

> A static {Toolset}OptionDefinitions class is not needed

1c. Service Interface and Implementation

File: src/Services/I{Toolset}Service.cs

Return type depends on operation type:

• Resource Graph queries → Task<ResourceQueryResults<MyModel>> (includes AreResultsTruncated flag)
• Data plane operations → Task<List<MyModel>>
• Write operations → Task<MyResultModel>

public interface I{Toolset}Service
{
    // Resource Graph read operation
    Task<ResourceQueryResults<MyModel>> GetResourcesAsync(
        string? myOption,
        string subscription,
        string? resourceGroup = null,
        string? tenant = null,
        RetryPolicyOptions? retryPolicy = null,
        CancellationToken cancellationToken = default);

    // Data plane operation (returns simple List)
    Task<List<MyDetail>> GetDetailsAsync(
        string resourceName,
        string subscription,
        string? tenant = null,
        RetryPolicyOptions? retryPolicy = null,
        CancellationToken cancellationToken = default);
}

File: src/Services/{Toolset}Service.cs

Choose base class:

• Operations that need Resource Graph (ARG) queries: inherit BaseAzureResourceService
• All other operations (ARM, data plane): inherit BaseAzureService

> BaseAzureResourceService extends BaseAzureService — neither is

> inherently read-only or write-only. The distinction is whether you

> need ARG querying functionality.

public class {Toolset}Service(ISubscriptionService subscriptionService, ITenantService tenantService)
    : BaseAzureResourceService(subscriptionService, tenantService), I{Toolset}Service
{
    public async Task<ResourceQueryResults<MyModel>> GetResourcesAsync(
        string? myOption,
        string subscription,
        string? resourceGroup = null,
        string? tenant = null,
        RetryPolicyOptions? retryPolicy = null,
        CancellationToken cancellationToken = default)
    {
        return await ExecuteResourceQueryAsync(
            "Microsoft.{Provider}/{resourceType}",
            resourceGroup,
            subscription,
            retryPolicy,
            ConvertToModel,
            tenant: tenant,
            cancellationToken: cancellationToken);
    }

    private static MyModel ConvertToModel(JsonElement item)
    {
        var data = MyModelData.FromJson(item);
        return new MyModel(
            Name: data.ResourceName,
            Id: data.ResourceId,
            Location: data.Location.ToString(),
            Tags: data.Tags as IReadOnlyDictionary<string, string>
        );
    }
}

For write operations (using direct ARM clients):

public class {Toolset}Service(ISubscriptionService subscriptionService, ITenantService tenantService)
    : BaseAzureService(tenantService), I{Toolset}Service
{
    private readonly ISubscriptionService _subscriptionService = subscriptionService
        ?? throw new ArgumentNullException(nameof(subscriptionService));

    public async Task<MyResource> CreateResourceAsync(
        string resourceName,
        string resourceGroup,
        string subscription,
        string? tenant = null,
        RetryPolicyOptions? retryPolicy = null,
        CancellationToken cancellationToken = default)
    {
        var subscriptionResource = await _subscriptionService.GetSubscription(subscription, tenant, retryPolicy);

        // CRITICAL: Use GetResourceGroupAsync with await
        var rgResource = await subscriptionResource.GetResourceGroupAsync(resourceGroup, cancellationToken);
        var resource = await rgResource.Value
            .GetMyResources()
            .GetAsync(resourceName, cancellationToken: cancellationToken);
        return resource.Value;
    }
}

Sovereign cloud rules:

• ARM/Resource Graph operations: cloud-aware automatically, no extra work
• Data plane endpoints: use TenantService.CloudConfiguration.CloudType switch — never hardcode URLs

Data plane endpoint pattern (required for services like Storage, Cosmos, Search):

public class MyService(ISubscriptionService subscriptionService, ITenantService tenantService)
    : BaseAzureResourceService(subscriptionService, tenantService), IMyService
{

    private async Task<MyDataPlaneClient> CreateDataPlaneClientAsync(
        string resourceName,
        string? tenant = null,
        RetryPolicyOptions? retryPolicy = null,
        CancellationToken cancellationToken = default)
    {
        var endpoint = GetResourceEndpoint(resourceName);
        var options = ConfigureRetryPolicy(AddDefaultPolicies(new MyClientOptions()), retryPolicy);
        options.Transport = new HttpClientTransport(TenantService.GetClient());
        return new MyDataPlaneClient(
            new Uri(endpoint),
            await GetCredential(tenant, cancellationToken),
            options);
    }

    private string GetResourceEndpoint(string resourceName)
    {
        return TenantService.CloudConfiguration.CloudType switch
        {
            AzureCloudConfiguration.AzureCloud.AzurePublicCloud =>
                $"https://{resourceName}.service.core.windows.net",
            AzureCloudConfiguration.AzureCloud.AzureChinaCloud =>
                $"https://{resourceName}.service.core.chinacloudapi.cn",
            AzureCloudConfiguration.AzureCloud.AzureUSGovernmentCloud =>
                $"https://{resourceName}.service.core.usgovcloudapi.net",
            _ => $"https://{resourceName}.service.core.windows.net"
        };
    }
}

Patterns and anti-patterns:

// ❌ Hardcoded public-cloud endpoint
var client = new BlobServiceClient(new($"https://{account}.blob.core.windows.net"), credential, options);

// ❌ Hardcoded connection string
var connectionString = $"AccountEndpoint=https://{server}.documents.azure.com:443/;...";

// ✅ Cloud-aware endpoint via switch expression
var endpoint = GetBlobEndpoint(account);
var client = new BlobServiceClient(new(endpoint), credential, options);

Reference implementations: StorageService, CosmosService, SearchService, ConfidentialLedgerService.

1d. Command Class

File: src/Commands/{Resource}/{Resource}{Operation}Command.cs

Required using statements:

using Azure.Mcp.Core.Commands.Subscription;
using Azure.Mcp.Core.Services.Azure.Subscription;
using Azure.Mcp.Tools.{Toolset}.Models;
using Azure.Mcp.Tools.{Toolset}.Options.{Resource};
using Azure.Mcp.Tools.{Toolset}.Services;
using Microsoft.Extensions.Logging;
using Microsoft.Mcp.Core.Commands;
using Microsoft.Mcp.Core.Models.Command;

[CommandMetadata(
    Id = "<generate-new-guid>",
    Name = "operation",
    Title = "Human Readable Title",
    Description = """
        What this command does. Include required options and return format.
        """,
    Destructive = false,
    Idempotent = true,
    OpenWorld = false,
    ReadOnly = true,
    Secret = false,
    LocalRequired = false)]
public sealed class {Resource}{Operation}Command(
    ILogger<{Resource}{Operation}Command> logger,
    I{Toolset}Service service,
    ISubscriptionResolver subscriptionResolver)
    : SubscriptionCommand<{Resource}{Operation}Options, {Resource}{Operation}Command.{Resource}{Operation}CommandResult>(subscriptionResolver)
{
    private readonly ILogger<{Resource}{Operation}Command> _logger = logger;
    private readonly I{Toolset}Service _service = service;

    public override async Task<CommandResponse> ExecuteAsync(
        CommandContext context, {Resource}{Operation}Options options, CancellationToken cancellationToken)
    {
        try
        {
            var results = await _service.GetResourcesAsync(
                options.MyOption,
                options.Subscription!,
                options.ResourceGroup,
                options.Tenant,
                options.RetryPolicy,
                cancellationToken);

            context.Response.Results = ResponseResult.Create(
                new {Resource}{Operation}CommandResult(results?.Results ?? [], results?.AreResultsTruncated ?? false),
                {Toolset}JsonContext.Default.{Resource}{Operation}CommandResult);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error in {Operation}. Subscription: {Subscription}",
                Name, options.Subscription);
            HandleException(context, ex);
        }

        return context.Response;
    }

    public record {Resource}{Operation}CommandResult(List<MyModel> Items, bool AreResultsTruncated);
}

Key points (two-generic pattern from docs/option-conversion.md):

• Two generic parameters: SubscriptionCommand<TOptions, TResult> — TResult is the command's result record
• ISubscriptionResolver injected via primary constructor and passed to base
• ExecuteAsync receives pre-bound TOptions options — no ParseResult parameter
• No RegisterOptions()/BindOptions() overrides needed — OptionBinder handles binding via [Option] attributes
• No manual Validate() call — framework validates based on nullability and ValidateOptions() override
• Result record is public (for JSON serialization context visibility) and declared inside the command class
• DO NOT log {@Options} — may expose sensitive information

Custom validation (required for semantic and security constraints beyond nullability):

public override void ValidateOptions({Resource}{Operation}Options options, ValidationResult validationResult)
{
    base.ValidateOptions(options, validationResult);  // checks --subscription

    // Required-field check
    if (string.IsNullOrEmpty(options.MyRequiredField))
    {
        validationResult.Errors.Add("--my-required-field is required.");
    }

    // Security: validate against the specific Azure resource's naming rules.
    // Prefer deterministic checks first (length + character/category checks).
    // Look up exact constraints at:
    // https://learn.microsoft.com/azure/azure-resource-manager/management/resource-name-rules
    //
    // Example for a Storage account name (3–24 lowercase alphanumeric only):
    if (options.Account is not null &&
        !IsValidStorageAccountName(options.Account))
    {
        validationResult.Errors.Add("--account must be 3–24 lowercase alphanumeric characters (storage account naming rule).");
    }
}

private static bool IsValidStorageAccountName(string value)
{
    if (value.Length is < 3 or > 24)
        return false;

    foreach (var ch in value)
    {
        if (!((ch >= 'a' && ch <= 'z') || (ch >= '0' && ch <= '9')))
            return false;
    }

    return true;
}

Intermediate base commands (only if you have shared cross-command logic):

// Use interface constraints for type-safe access to shared options
public abstract class Base{Toolset}Command<
    [DynamicallyAccessedMembers(TrimAnnotations.CommandAnnotations)] TOptions, TResult>(
    ISubscriptionResolver subscriptionResolver)
    : SubscriptionCommand<TOptions, TResult>(subscriptionResolver)
    where TOptions : class, ISubscriptionOption, I{Toolset}Option
{
    public override void ValidateOptions(TOptions options, ValidationResult validationResult)
    {
        base.ValidateOptions(options, validationResult);
        // Shared validation using options.SharedProperty
    }
}

1e. JSON Serialization Context

File: src/Commands/{Toolset}JsonContext.cs

[JsonSerializable(typeof({Resource}{Operation}Command.{Resource}{Operation}CommandResult))]
[JsonSerializable(typeof(MyModel))]
[JsonSourceGenerationOptions(
    PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase,
    DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull)]
internal partial class {Toolset}JsonContext : JsonSerializerContext;

Guidelines:

• Only include types actually serialized as top-level result payloads
• Keep [JsonSerializable] attributes sorted by typeof model name
• Use one context per toolset always
• Filename must match class name ({Toolset}JsonContext.cs)
• Use {Toolset}JsonContext.Default.{CommandResult} when serializing — never JsonSerializer.Deserialize<T>() without a context

1f. Register Command

File: src/{Toolset}Setup.cs

public class {Toolset}Setup : IAreaSetup
{
    public string Name => "{toolset}";

    public string Title => "Manage Azure {Toolset}";

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<I{Toolset}Service, {Toolset}Service>();

        // Register all commands as singletons
        services.AddSingleton<{Resource}{Operation}Command>();
    }

    public CommandGroup RegisterCommands(IServiceProvider serviceProvider)
    {
        var root = new CommandGroup(Name,
            """
            {Toolset} operations - description of what this toolset covers.
            """,
            Title);

        var resource = new CommandGroup("{resource}", "{Resource} operations description");
        root.AddSubGroup(resource);
        resource.AddCommand<{Resource}{Operation}Command>(serviceProvider);

        return root;
    }
}

Also register the toolset in servers/Azure.Mcp.Server/src/Program.cs:

private static IAreaSetup[] RegisterAreas()
{
    return [
        // ... existing toolsets (alphabetical order) ...
        new Azure.Mcp.Tools.{Toolset}.{Toolset}Setup(),
        // ... more toolsets ...
    ];
}

The RegisterAreas() list must remain alphabetically sorted (excluding the #if !BUILD_NATIVE block).

Command group naming: concatenated lowercase or dash-separated. Never underscores.

• ✅ Good: "entraadmin", "resourcegroup", "storageaccount", "entra-admin"
• ❌ Bad: "entra_admin", "resource_group", "storage_account"

Command hierarchy patterns and anti-patterns:

• ✅ Good: azmcp postgres server param set (command groups: server → param, operation: set)
• ❌ Bad: azmcp postgres server setparam (mixed operation setparam at same level)
• ✅ Good: azmcp storage blob upload permission set
• ❌ Bad: azmcp storage blobupload

This pattern improves discoverability and allows grouping related operations.

GATE: dotnet build tools/Azure.Mcp.Tools.{Toolset}/src must pass with 0 errors.

Phase 2: Unit Tests

File: tests/Azure.Mcp.Tools.{Toolset}.Tests/{Resource}/{Resource}{Operation}CommandTests.cs

Required test methods

using System.Net;
using Azure.Mcp.Core.Services.Azure;
using Azure.Mcp.Tests.Commands;
using Azure.Mcp.Tools.{Toolset}.Commands;
using Azure.Mcp.Tools.{Toolset}.Commands.{Resource};
using Azure.Mcp.Tools.{Toolset}.Models;
using Azure.Mcp.Tools.{Toolset}.Services;
using Microsoft.Mcp.Core.Options;
using NSubstitute;
using NSubstitute.ExceptionExtensions;
using Xunit;

namespace Azure.Mcp.Tools.{Toolset}.Tests.{Resource};

public class {Resource}{Operation}CommandTests
    : SubscriptionCommandUnitTestsBase<{Resource}{Operation}Command, I{Toolset}Service>
{
    [Fact]
    public void Constructor_InitializesCommandCorrectly()
    {
        var command = Command.GetCommand();
        Assert.Equal("operation", command.Name);
        Assert.NotNull(command.Description);
        Assert.NotEmpty(command.Description);
    }

    [Theory]
    [InlineData("--my-option val --subscription sub123", true)]
    [InlineData("--subscription sub123", true)]  // my-option is optional
    [InlineData("", false)]  // missing args
    public async Task ExecuteAsync_ValidatesInputCorrectly(string args, bool shouldSucceed)
    {
        if (shouldSucceed)
        {
            Service.GetResourcesAsync(
                Arg.Any<string?>(), Arg.Any<string>(), Arg.Any<string?>(),
                Arg.Any<string?>(), Arg.Any<RetryPolicyOptions?>(),
                Arg.Any<CancellationToken>())
                .Returns(new ResourceQueryResults<MyModel>([], false));
        }

        var response = await ExecuteCommandAsync(args);

        Assert.Equal(shouldSucceed ? HttpStatusCode.OK : HttpStatusCode.BadRequest, response.Status);
        if (!shouldSucceed)
            Assert.Contains("required", response.Message.ToLower());
    }

    [Fact]
    public async Task ExecuteAsync_DeserializationValidation()
    {
        Service.GetResourcesAsync(
            Arg.Any<string?>(), Arg.Any<string>(), Arg.Any<string?>(),
            Arg.Any<string?>(), Arg.Any<RetryPolicyOptions?>(),
            Arg.Any<CancellationToken>())
            .Returns(new ResourceQueryResults<MyModel>([], false));

        var response = await ExecuteCommandAsync("--subscription", "sub123");

        var result = ValidateAndDeserializeResponse(
            response, {Toolset}JsonContext.Default.{Resource}{Operation}CommandResult);
        Assert.Empty(result.Items);
    }

    [Fact]
    public async Task ExecuteAsync_HandlesServiceErrors()
    {
        Service.GetResourcesAsync(
            Arg.Any<string?>(), Arg.Any<string>(), Arg.Any<string?>(),
            Arg.Any<string?>(), Arg.Any<RetryPolicyOptions?>(),
            Arg.Any<CancellationToken>())
            .ThrowsAsync(new Exception("Test error"));

        var response = await ExecuteCommandAsync("--subscription", "sub123", "--my-option", "val");

        Assert.Equal(HttpStatusCode.InternalServerError, response.Status);
        Assert.Contains("Test error", response.Message);
        Assert.Contains("troubleshooting", response.Message);
    }

    [Fact]
    public async Task ExecuteAsync_HandlesNotFound()
    {
        Service.GetResourcesAsync(
            Arg.Any<string?>(), Arg.Any<string>(), Arg.Any<string?>(),
            Arg.Any<string?>(), Arg.Any<RetryPolicyOptions?>(),
            Arg.Any<CancellationToken>())
            .ThrowsAsync(new RequestFailedException((int)HttpStatusCode.NotFound, "Resource not found"));

        var response = await ExecuteCommandAsync("--subscription", "sub123", "--my-option", "val");

        Assert.Equal(HttpStatusCode.NotFound, response.Status);
        Assert.Contains("Resource not found", response.Message);
    }
}

Critical: Choose the correct test base class:

• Commands extending SubscriptionCommand → use SubscriptionCommandUnitTestsBase<TCommand, TService>
• Commands extending BaseCommand directly (no subscription) → use CommandUnitTestsBase<TCommand, TService>

Using the wrong base class will cause DI failures.

Prefer string args over constructing options directly. Using ExecuteCommandAsync("--account", ...) tests the full pipeline: [Option] attribute registration, OptionBinder parsing, and SubscriptionResolver post-processing.

Mock rules:

• Use Arg.Any<CancellationToken>() for CancellationToken in mocks
• Use TestContext.Current.CancellationToken when invoking real code
• Use Arg.Is(value) or the value directly for specific match assertions
• Never pass CancellationToken.None or default in test code

Deserialization rules:

• Use {Toolset}JsonContext.Default.{Operation}CommandResult for deserialization — never define custom test models
• ✅ ValidateAndDeserializeResponse(response, {Toolset}JsonContext.Default.{Operation}CommandResult)
• ❌ JsonSerializer.Deserialize<TestModel>(json)

GATE: dotnet test tools/Azure.Mcp.Tools.{Toolset}/tests --filter "FullyQualifiedName~{Resource}{Operation}CommandTests" must pass.

Phase 3: Live Tests (Azure service commands only)

Skip this phase for non-Azure commands (CLI wrappers, best practices, documentation tools).

3a. Test Infrastructure

File: tests/test-resources.bicep

targetScope = 'resourceGroup'

@minLength(3)
@maxLength(17)
param baseName string = resourceGroup().name

param testApplicationOid string = deployer().objectId
param location string = resourceGroup().location

resource myResource 'Microsoft.{Provider}/{type}@{api-version}' = {
  name: baseName
  location: location
  properties: { /* minimal config */ }
}

resource roleAssignment 'Microsoft.Authorization/roleAssignments@2022-04-01' = {
  name: guid(roleDefinition.id, testApplicationOid, myResource.id)
  scope: myResource
  properties: {
    principalId: testApplicationOid
    roleDefinitionId: roleDefinition.id
  }
}

output resourceName string = myResource.name

File: tests/test-resources-post.ps1 (required even if empty logic)

[CmdletBinding()]
param (
    [Parameter(Mandatory)] [hashtable] $DeploymentOutputs,
    [Parameter(Mandatory)] [hashtable] $AdditionalParameters
)
Write-Host "{Toolset} post-deployment setup completed."

Validate: az bicep build --file tools/Azure.Mcp.Tools.{Toolset}/tests/test-resources.bicep

3b. Live Test Class

File: tests/Azure.Mcp.Tools.{Toolset}.Tests/{Toolset}CommandTests.cs

public class {Toolset}CommandTests(ITestOutputHelper output, TestProxyFixture fixture, LiveServerFixture liveServerFixture)
    : RecordedCommandTestsBase(output, fixture, liveServerFixture)
{
    [Fact]
    public async Task {Resource}{Operation}_ReturnsExpectedResult()
    {
        var result = await CallToolAsync(
            "{toolset}_{resource}_{operation}",
            new()
            {
                ["subscription"] = SubscriptionId,
                ["resource-group"] = ResourceGroupName,
            });

        Assert.NotNull(result);
        var items = result.Value.AssertProperty("items");
        Assert.Equal(JsonValueKind.Array, items.ValueKind);
    }
}

3c. Record and Verify

Create assets.json

Create assets.json if it doesn't exist:

{
  "AssetsRepo": "Azure/azure-sdk-assets",
  "AssetsRepoPrefixPath": "",
  "TagPrefix": "Azure.Mcp.Tools.{Toolset}.Tests",
  "Tag": ""
}

Deploy

eng/common/TestResources/New-TestResources.ps1 `
   -TestResourcesDirectory tools/Azure.Mcp.Tools.{Toolset}

Record tests

 dotnet test tools\Azure.Mcp.Tools.{Toolset}\tests\Azure.Mcp.Tools.{Toolset}.Tests `
   --filter "FullyQualifiedName~{Resource}{Operation}"

Push recordings

.proxy\Azure.Sdk.Tools.TestProxy push `
  -a tools\Azure.Mcp.Tools.{Toolset}\tests\Azure.Mcp.Tools.{Toolset}.Tests\assets.json

Verify playback

Change TestMode to "Playback" in .testsettings.json, then re-run tests

3c-1. Recorded Test Pitfalls

These are common causes of recorded test failures. Always verify playback passes after recording.

Always pass Settings.TenantId in live test calls

If the test subscription lives in a non-default tenant, the command will fail with InvalidAuthenticationTokenTenant. Include tenant when your subscription requires it:

var result = await CallToolAsync(
    "{toolset}_{resource}_{operation}",
    new()
    {
        { "subscription", Settings.SubscriptionId },
        { "resource-group", Settings.ResourceGroupName },
        { "tenant", Settings.TenantId }  // Always include
    });

Use RegisterOrRetrieveVariable for all dynamic values

Any non-deterministic value (Guid.NewGuid(), DateTime.Now) must be wrapped so the same value is used in both Record and Playback runs:

// ✅ Value is recorded and replayed deterministically
var topicName = RegisterOrRetrieveVariable("create_topic_name", $"topic-{Guid.NewGuid():N}"[..24]);

// ❌ Different GUID each run — breaks playback request matching
var topicName = $"topic-{Guid.NewGuid():N}"[..24];

Assertions must survive sanitization

Recording sanitizers replace sensitive values (resource names, IDs, endpoints) with placeholders like "Sanitized". Your assertion strategy depends on your test class sanitizer configuration:

| Approach | When to use | Example toolsets |

|----------|-------------|-----------------|

| Exact name assert | Your sanitizers do NOT replace the resource name | KeyVault, FunctionApp |

| Structural assert (AssertProperty) | Your sanitizers DO replace the name | EventGrid |

| SanitizeAndRecord helper | You need exact asserts AND have aggressive sanitizers | ManagedLustre |

How to check: After recording, inspect the session recording JSON (use .proxy/Azure.Sdk.Tools.TestProxy.exe config locate -a <assets.json>). If the "name" field shows "Sanitized", you cannot use exact name asserts without the SanitizeAndRecord pattern.

// Safe assertions that survive any sanitizer configuration:
topic.AssertProperty("name");  // Checks existence only
Assert.Equal("Succeeded", topic.GetProperty("provisioningState").GetString());  // Enum values aren't sanitized
Assert.Equal(JsonValueKind.Object, topic.ValueKind);  // Type checks

Credential type in .testsettings.json

Deploy-TestResources.ps1 sets AZURE_TOKEN_CREDENTIALS=AzurePowerShellCredential. If the MCP server subprocess cannot access the PowerShell credential cache (common on some machines), switch to AzureCliCredential:

"EnvironmentVariables": {
    "AZURE_TOKEN_CREDENTIALS": "AzureCliCredential"
}

Ensure az login --tenant <tenant-id> is active. If recording fails with credential errors from the subprocess, this is the likely fix.

Redeploy if resource group is missing

Test resource groups are auto-deleted after 12 hours. If tests fail with ResourceGroupNotFound, redeploy:

./eng/scripts/Deploy-TestResources.ps1 -Paths {Toolset}

3d. Test Project Configuration (Critical)

The test .csproj must have these specific settings or tests will fail with "azmcp.exe not found":

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <IsPackable>false</IsPackable>
    <IsTestProject>true</IsTestProject>
    <OutputType>Exe</OutputType>
    <HasLiveTests>true</HasLiveTests>
    <HasUnitTests>true</HasUnitTests>
  </PropertyGroup>

  <ItemGroup>
    <ProjectReference Include="..\..\src\Azure.Mcp.Tools.{Toolset}.csproj" />
    <ProjectReference Include="$(RepoRoot)servers\Azure.Mcp.Server\src\Azure.Mcp.Server.csproj" />
  </ItemGroup>
</Project>

⚠️ Common mistake: Referencing only the toolset project. Live tests must also reference Azure.Mcp.Server.csproj.

3e. IAsyncLifetime Pattern

If your live test class needs IAsyncLifetime or overrides Dispose, you must call base.Dispose():

public class MyCommandTests(ITestOutputHelper output, TestProxyFixture fixture, LiveServerFixture liveServerFixture)
    : RecordedCommandTestsBase(output, fixture, liveServerFixture), IAsyncLifetime
{
    public ValueTask DisposeAsync()
    {
        base.Dispose();
        return ValueTask.CompletedTask;
    }
}

Failure to call base.Dispose() prevents request/response data from being written to failing test results.

GATE: Tests pass in both Record and Playback modes.

Phase 4: Validation

Run all checks in order. All must pass.

# 1. Build
dotnet build tools/Azure.Mcp.Tools.{Toolset}/src

# 2. Format
dotnet format Microsoft.Mcp.slnx --verify-no-changes --include "tools/Azure.Mcp.Tools.{Toolset}/**"

# 3. All unit tests (including existing — no regressions)
dotnet test tools/Azure.Mcp.Tools.{Toolset}/tests

# 4. Spell check
.\eng\common\spelling\Invoke-Cspell.ps1

# 5. Full verification
./eng/scripts/Build-Local.ps1 -UsePaths -VerifyNpx

# 6. AOT/Native build (required for AOT-compatible toolsets)
./eng/scripts/Build-Local.ps1 -BuildNative

If AOT fails (common for new Azure SDK dependencies):

• Move toolset setup in Program.cs under #if !BUILD_NATIVE
• Add ProjectReference-Remove condition in Azure.Mcp.Server.csproj

GATE: All 6 checks green.

Phase 5: Documentation

5a. Command Reference

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

Add command in alphabetical order within service section. Then regenerate metadata:

./eng/scripts/Update-AzCommandsMetadata.ps1

5b. Test Prompts

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

Add 2-3 natural language prompts in alphabetical order:

| {toolset}_{resource}_{operation} | Natural language prompt |

5c. Changelog Entry

Follow docs/changelog-entries.md. Create entry using ./eng/scripts/New-ChangelogEntry.ps1 or manually. Use -ChangelogPath servers/Azure.Mcp.Server/CHANGELOG.md.

5d. README Updates

• servers/Azure.Mcp.Server/README.md: Update the supported services table (line ~1189) and add example prompts in the "What can you do" section (line ~898). This file is processed by eng/scripts/Process-PackageReadMe.ps1 into package-specific outputs (NuGet, VSIX, npm, PyPI) so a single update covers all distribution channels.

5e. CODEOWNERS

File: .github/CODEOWNERS

Add your new toolset path with appropriate team ownership:

/tools/Azure.Mcp.Tools.{Toolset}/ @your-team

5f. Consolidated Tools Registration

File: servers/Azure.Mcp.Server/src/Resources/consolidated-tools.json

Add your new tool(s) to the consolidated tools JSON. Use the following command to find the correct tool name:

cd servers/Azure.Mcp.Server/src/bin/Debug/net10.0
./azmcp[.exe] tools list --name --namespace <tool_area>

Documentation Standards:

• Use consistent command paths in all documentation (e.g., azmcp sql db show)
• Always run .\eng\scripts\Update-AzCommandsMetadata.ps1 after updating azmcp-commands.md (CI will fail if skipped)
• Organize example prompts by service in README.md under service-specific sections
• Maintain alphabetical sorting in e2eTestPrompts.md (service sections AND tool names within each table)
• Include parameter descriptions and required vs optional indicators in azmcp-commands.md

GATE: ./eng/scripts/Update-AzCommandsMetadata.ps1 succeeds.

Phase 6: Tool Description Evaluation

Now that test prompts are written (Phase 5b), validate your command description against them using the ToolDescriptionEvaluator.

> Full documentation: See eng/tools/ToolDescriptionEvaluator/Quickstart.md for setup details.

Prerequisites

Set your Azure OpenAI endpoint and API key as environment variables:

$env:AOAI_ENDPOINT = "https://<your-resource>.openai.azure.com/openai/deployments/<embeddings-deployment-name>/embeddings?api-version=<api-version>"
$env:TEXT_EMBEDDING_API_KEY = "your_api_key_here"

> For internal contributors, refer to the Before creating a pull request section of this document to use our team's deployment and credentials.

Option A: Test a single tool description (fastest for development)

Use --test-single-tool mode to validate your description without building the full server:

# Test a single tool description against one prompt
dotnet run --project eng/tools/ToolDescriptionEvaluator/src -- --test-single-tool `
  --tool-description "Your command description" `
  --prompt "user query"

# Test against multiple prompts (recommended — test 2-3 phrasings)
dotnet run --project eng/tools/ToolDescriptionEvaluator/src -- --test-single-tool `
  --tool-description "Lists all user-assigned managed identities in a subscription" `
  --prompt "show me my managed identities" `
  --prompt "list managed identities in my subscription" `
  --prompt "what identities do I have"

Option B: Run the full evaluator against your service area

This builds the server and tests all tools in your area against the e2eTestPrompts.md file:

# Run evaluator for your specific service area
pushd eng/tools/ToolDescriptionEvaluator
./scripts/Run-ToolDescriptionEvaluator.ps1 -Area "{Toolset}"

# Build the Azure.Mcp.Server as part of the run
./scripts/Run-ToolDescriptionEvaluator.ps1 -Area "{Toolset}" -BuildAzureMcp

# Run for all Azure MCP Server tools (slower)
./scripts/Run-ToolDescriptionEvaluator.ps1
popd

Interpreting Results

Target: Top 3 ranking and confidence score ≥ 0.4.

• Score >= 0.6: Excellent — tool will be reliably selected
• Score 0.4 - 0.6: Acceptable — tool should be selected in most cases
• Score < 0.4: Poor — description needs improvement

Improving Low Scores

If score is low, improve the Description in [CommandMetadata]:

• Include verbs users would say ("list", "get", "show", "configure")
• Mention specific resource types and Azure service names
• Describe what the output contains
• Consider common synonyms and alternative phrasings
• Avoid overly generic descriptions that could match many tools

Custom prompts file formats:

• Markdown: Same table format as servers/Azure.Mcp.Server/docs/e2eTestPrompts.md
• JSON: { "azmcp-your-command": ["prompt1", "prompt2"] }

GATE: Score meets threshold (≥ 0.4, top 3 ranking). If the evaluator is not available (no Azure OpenAI credentials), manually verify the description is specific and action-oriented.

Phase 7: PR Checklist

Before creating the PR, verify all of these:

Core Implementation

• [ ] Options class is flat POCO with [Option] attributes implementing ISubscriptionOption
• [ ] Command inherits SubscriptionCommand<TOptions, TResult> with ISubscriptionResolver
• [ ] ExecuteAsync takes (CommandContext, TOptions, CancellationToken) — no ParseResult
• [ ] Service interface and implementation complete
• [ ] All async methods include CancellationToken parameter as final argument
• [ ] Unit tests cover all paths (using SubscriptionCommandUnitTestsBase)
• [ ] Integration/live tests added
• [ ] Command registered as singleton in {Toolset}Setup.cs ConfigureServices
• [ ] Command added to group in {Toolset}Setup.cs RegisterCommands
• [ ] Follows file structure exactly
• [ ] Error handling implemented with HandleException(context, ex)
• [ ] New tools added to consolidated-tools.json
• [ ] Documentation complete

Package and Project Setup

• [ ] Azure SDK package added to both Directory.Packages.props AND .csproj
• [ ] Package version consistency (same version in both files)
• [ ] Projects added to Microsoft.Mcp.slnx and Azure.Mcp.Server.slnx
• [ ] Toolset registered in Program.cs RegisterAreas() (alphabetical)
• [ ] JSON serialization context includes all new model types

Build and Code Quality

• [ ] Build passes (dotnet build)
• [ ] No compiler warnings
• [ ] Format clean (dotnet format --verify-no-changes)
• [ ] All unit tests pass (no regressions)
• [ ] All live tests pass in Playback mode
• [ ] Recordings pushed and assets.json committed
• [ ] Spell check passes (.\eng\common\spelling\Invoke-Cspell.ps1)
• [ ] ToolDescriptionEvaluator score ≥ 0.4
• [ ] AOT compilation verified (./eng/scripts/Build-Local.ps1 -BuildNative)
• [ ] One tool per PR

Azure SDK Integration

• [ ] All Azure SDK property names verified and correct
• [ ] Resource access patterns use collections (e.g., .GetSqlServers().GetAsync())
• [ ] CancellationToken passed to all async SDK calls
• [ ] Subscription resolution uses ISubscriptionResolver (injected in constructor)
• [ ] Service constructor includes ISubscriptionService injection

Documentation

• [ ] azmcp-commands.md updated with command documentation
• [ ] Update-AzCommandsMetadata.ps1 executed (CI will fail if skipped)
• [ ] e2eTestPrompts.md updated (alphabetical order maintained)
• [ ] Changelog entry created (use -ChangelogPath)
• [ ] servers/Azure.Mcp.Server/README.md updated with example prompts and service listing
• [ ] .github/CODEOWNERS entry added for new toolset

Transport-Agnostic Requirements (Remote MCP Server Compatibility)

• [ ] Commands are stateless — no per-request state in instance fields
• [ ] Commands are thread-safe for multi-user concurrency
• [ ] No transport checks (Environment.GetEnvironmentVariable("ASPNETCORE_URLS"), HttpContext)
• [ ] Error messages are context-aware (include OBO-specific guidance where applicable)
• [ ] Uses IAzureTokenCredentialProvider for all authentication (not direct DefaultAzureCredential)

Security

• [ ] ValidateOptions enforces format, length, and allowed-value constraints on all inputs — not only nullability
• [ ] No raw option objects logged — only individually named, known-safe parameters (e.g., options.Subscription, Name)
• [ ] No user input concatenated directly into URLs, resource identifiers, or command strings without prior allowlist validation
• [ ] Data-plane endpoints validated with EndpointValidator.ValidateAzureServiceEndpoint (Azure services), ValidateExternalUrl (known external hosts), or ValidatePublicTargetUrl (arbitrary user-supplied targets) — never derived from raw user input without validation
• [ ] Error messages are actionable but do not expose internal state, stack traces, or sensitive field values to callers
• [ ] Sensitive fields (keys, secrets, connection strings) are not returned in standard list/get responses unless the command is explicitly marked Secret = true
• [ ] Negative unit tests included for malformed, oversized, or hostile inputs
• [ ] If AI was used to generate any code in this PR, the AI prompt included security requirements and the output was reviewed for compliance with the Security Requirements section

Required Files Checklist

Verify all files exist for your command:

• src/Options/{Resource}/{Resource}{Operation}Options.cs (flat POCO with [Option] attributes)
• src/Commands/{Resource}/{Resource}{Operation}Command.cs
• src/Services/I{Toolset}Service.cs
• src/Services/{Toolset}Service.cs
• src/Commands/{Toolset}JsonContext.cs
• src/{Toolset}Setup.cs (implements IAreaSetup, registers commands + services)
• tests/Azure.Mcp.Tools.{Toolset}.Tests/{Resource}/{Resource}{Operation}CommandTests.cs
• tests/Azure.Mcp.Tools.{Toolset}.Tests/{Toolset}CommandTests.cs (live tests, Azure only)
• tests/test-resources.bicep (Azure service commands only)

10. tests/test-resources-post.ps1 (Azure service commands only)

Quick Reference: Naming Conventions

| Element | Pattern | Example |

|---------|---------|---------|

| Command class | {Resource}{SubResource?}{Operation}Command | StorageAccountGetCommand |

| Options class | {Resource}{Operation}Options | StorageAccountGetOptions |

| Test class | {Resource}{Operation}CommandTests | StorageAccountGetCommandTests |

| CLI command | azmcp {service} {resource} {operation} | azmcp storage account get |

| Command group | Concatenated lowercase | "resourcegroup", "storageaccount" |

| Option flag | --kebab-case | --resource-group, --account |

Naming rules:

• Resource = top-level domain entity (Server, Database, FileSystem)
• SubResource (optional) = nested concept (Config, Param, SubnetSize)
• Operation = action or computed intent (List, Get, Set, Show, Delete, Calculate)
• ✅ ServerListCommand, ServerConfigGetCommand, FileSystemSubnetSizeCommand
• ❌ GetConfigCommand (missing resource), ListServerCommand (verb precedes resource)

Quick Reference: ToolMetadata Properties

| Property | true | false |

|----------|--------|---------|

| Destructive | Deletes/modifies resources | Read-only or safe operations |

| Idempotent | Same result on repeated calls | Accumulates effects |

| OpenWorld | Unpredictable external systems | Well-defined Azure APIs |

| ReadOnly | Only queries data | Creates/updates/deletes |

| Secret | Returns credentials/keys | Returns non-sensitive data |

| LocalRequired | Needs local tools/files | Remote API calls only |

Detailed ToolMetadata guidance:

• OpenWorld: Most Azure resource commands use false because they operate within the well-defined domain of Azure Resource Manager APIs. Only use true for commands interacting with truly unpredictable external systems outside Azure's control.
• false: Storage accounts, databases, VMs, schema definitions, best practices guides
• true: External web scraping, unstructured third-party data sources (rare)

• Destructive: Set true for commands that delete, modify, or could cause data loss.
• true: Delete database, reset keys, purge storage, modify critical settings
• false: List resources, show configuration, query data, get status

• Idempotent: Can it be safely called multiple times with same params?
• true: Set config to specific value, create named resource (with "already exists" handled)
• false: Generate new keys, create resources with auto-generated names, append logs

• Secret: Does it return sensitive data?
• true: Get storage account keys, show connection strings, retrieve certificates
• false: List public resources, show non-sensitive config

• LocalRequired: Does it need local tools/files?
• true: Azure CLI wrappers, local file operations, tools requiring local installation
• false: Pure cloud API commands (most Azure resource commands)

⚠️ Metadata Validation Checklist

After setting [CommandMetadata] properties, cross-check each value against these heuristics. Do not proceed if any check fails — correct the metadata first.

Destructive:

• If the command name contains delete, remove, purge, reset, revoke, or update → must be true
• If the command name contains list, get, show, query, or describe → must be false
• If the command creates resources that replace existing ones → should be true

Idempotent:

• If calling the command twice with the same inputs produces different results → must be false
• If the command generates new keys, rotates secrets, or creates auto-named resources → must be false
• If the command returns the same data or sets the same state regardless of repetition → must be true

OpenWorld:

• If the command only calls Azure Resource Manager, Microsoft Graph, or other well-defined Microsoft APIs → must be false
• Only set true if the command interacts with user-controlled external systems, arbitrary URLs, or unpredictable third-party services

ReadOnly:

• If the command can modify state (create, update, delete, write, upload) → must be false
• If the command only retrieves information → must be true
• Must be the logical inverse of Destructive for most commands (both can be false for create operations)

Secret:

• If the command name or resource contains credential, secret, key, password, certificate, token, or connectionstring → default to true unless the command provably cannot expose any sensitive information
• If the command returns access keys, connection strings, secret values, or credential metadata (IDs, expiry, types) → must be true
• If the command only lists resource names or non-sensitive configuration → false
• When in doubt, set true — it is safer to over-classify than to expose credentials without the Secret flag

LocalRequired:

• If the command makes only remote API calls → must be false
• Only set true if the command requires local file system access, local CLI tools, or locally installed software

Guidelines:

• Fully declare all ToolMetadata properties even if using defaults
• Only override GetErrorMessage and GetStatusCode if logic differs from base class
• Commands returning arrays return empty array [] for null/empty service results

Quick Reference: Common Pitfalls

Never do (new pattern):

• ❌ subscriptionId → ✅ subscription
• ❌ Options without [Option] attribute → ✅ Always add [Option("description")] or [Option(OptionDescriptions.X)]
• ❌ Inherit options from base class → ✅ Flat POCO implementing ISubscriptionOption
• ❌ Manual RegisterOptions/BindOptions in new commands → ✅ Use [Option] attributes (automatic)
• ❌ ExecuteAsync(context, parseResult, ct) → ✅ ExecuteAsync(context, options, ct)
• ❌ Call Validate(parseResult.CommandResult, ...) → ✅ Override ValidateOptions(options, result) if needed
• ❌ Hardcoded cloud URLs → ✅ CloudConfiguration.CloudType switch
• ❌ Logging {@Options} → ✅ Log only safe parameters individually
• ❌ Underscores in group names → ✅ Concatenated lowercase or dash-separated
• ❌ Missing CancellationToken → ✅ Always the final parameter
• ❌ CancellationToken.None in tests → ✅ TestContext.Current.CancellationToken
• ❌ Skip base.Dispose() in tests → ✅ Always call when overriding
• ❌ Skip live test infrastructure for Azure commands → ✅ Create test-resources.bicep early
• ❌ CommandUnitTestsBase for subscription commands → ✅ Use SubscriptionCommandUnitTestsBase
• ❌ [Option(Name = "my-option")] when default matches → ✅ Only use Name = when kebab-case conversion is wrong
• ❌ Forget to register command as singleton → ✅ services.AddSingleton<MyCommand>() in ConfigureServices

Always do:

• Use [Option] attributes on flat options POCO (implements ISubscriptionOption)
• Use SubscriptionCommand<TOptions, TResult> with ISubscriptionResolver injection
• Inherit SubscriptionCommandUnitTestsBase<TCommand, TService> for unit tests
• Create test infrastructure before implementing live tests
• Follow exact file structure and naming
• Make command classes sealed
• Use primary constructors
• Register commands AND services in {Toolset}Setup.cs ConfigureServices
• Register toolset in Program.cs RegisterAreas()
• Handle all error cases with HandleException
• Use consistent resource naming patterns
• Reference docs/option-conversion.md when working with legacy one-generic commands

Reference: SDK Property Name Discovery

Azure SDK property names frequently differ from documentation or expected names. Always verify actual property names before implementation.

Verification Steps: CRITICAL: Verify SDK Property Names Before Implementation

• Use IntelliSense First: Let the IDE show you what's actually available
• Inspect Assemblies When Needed: If you get compilation errors about missing properties:

   $dll = Get-ChildItem -Path "." -Recurse -Filter "Azure.ResourceManager.*.dll" | Select-Object -First 1 -ExpandProperty FullName
   Add-Type -Path $dll
   [Azure.ResourceManager.Compute.Models.VirtualMachineExtensionInstanceView].GetProperties() | Select-Object Name, PropertyType

Common Property Name Patterns

• Extension types: VirtualMachineExtensionInstanceViewType (not TypeHandlerType)
• Time properties: Often use StartOn/LastActionOn (not StartTime/LastActionTime)
• Date properties: May use CreatedOn (not CreationDate or CreateDate)
• Location: Usually Location.Name or Location.ToString() (Location is an object, not a string)

Properties That May Not Exist

• Some properties shown in REST API may not exist in .NET SDK models
• Set values to null if the property truly doesn't exist in the data model
• Don't try to derive missing data from other sources unless explicitly required
• Document why a property is set to null in comments

Dictionary Type Casting for Tags

// ✅ Correct: Cast to IReadOnlyDictionary
Tags: data.Tags as IReadOnlyDictionary<string, string>

// ❌ Wrong: Direct assignment causes CS1503
Tags: data.Tags

Reference: ARM Compilation Error Troubleshooting

Common Errors and Fixes

cannot convert from 'CancellationToken' to 'string'