diff --git a/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/APIView/ApiViewHandlers.cs b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/APIView/ApiViewHandlers.cs
new file mode 100644
index 00000000000..6e0e8099901
--- /dev/null
+++ b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/APIView/ApiViewHandlers.cs
@@ -0,0 +1,96 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Azure.Sdk.Tools.Cli.Models;
+using Azure.Sdk.Tools.Cli.Models.Responses;
+
+namespace Azure.Sdk.Tools.Mock.Handlers.APIView;
+
+/// <summary>
+/// Mock handler for azsdk_apiview_get_comments. Returns a small fixed comment payload so
+/// callers can exercise the "consume APIView feedback" path deterministically.
+/// </summary>
+public class ApiViewGetCommentsHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_apiview_get_comments";
+
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new APIViewResponse
+    {
+        Message = "Retrieved APIView comments",
+        Language = arguments?.GetValueOrDefault("language")?.ToString() ?? ".NET",
+        PackageName = arguments?.GetValueOrDefault("packageName")?.ToString() ?? "Azure.Template.Contoso",
+        Result = new[]
+        {
+            new
+            {
+                id = "comment-1",
+                line = 42,
+                text = "Consider renaming this property for clarity.",
+                author = "reviewer@microsoft.com",
+                resolved = false
+            }
+        }
+    };
+}
+
+/// <summary>
+/// Mock handler for azsdk_apiview_get_review_url. Returns a deterministic review URL for the
+/// requested package + language.
+/// </summary>
+public class ApiViewGetReviewUrlHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_apiview_get_review_url";
+
+    public CommandResponse Handle(Dictionary<string, object?>? arguments)
+    {
+        var language = arguments?.GetValueOrDefault("language")?.ToString() ?? "dotnet";
+        var package = arguments?.GetValueOrDefault("packageName")?.ToString() ?? "Azure.Template.Contoso";
+        return new APIViewResponse
+        {
+            Message = "APIView URL resolved",
+            Language = language,
+            PackageName = package,
+            Result = $"https://apiview.dev/Assemblies/Review/mock-{language}-{package}".ToLowerInvariant()
+        };
+    }
+}
+
+/// <summary>
+/// Mock handler for azsdk_apiview_request_copilot_review. Returns a deterministic job ID
+/// callers can poll with azsdk_apiview_get_copilot_review.
+/// </summary>
+public class ApiViewRequestCopilotReviewHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_apiview_request_copilot_review";
+
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new APIViewResponse
+    {
+        Message = "Copilot review submitted",
+        Language = arguments?.GetValueOrDefault("language")?.ToString() ?? ".NET",
+        PackageName = arguments?.GetValueOrDefault("packageName")?.ToString() ?? "Azure.Template.Contoso",
+        Result = "mock-copilot-job-00000001"
+    };
+}
+
+/// <summary>
+/// Mock handler for azsdk_apiview_get_copilot_review. Returns a "completed" review with a
+/// single sample comment.
+/// </summary>
+public class ApiViewGetCopilotReviewHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_apiview_get_copilot_review";
+
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new APIViewResponse
+    {
+        Message = "Copilot review complete",
+        Result = new
+        {
+            jobId = arguments?.GetValueOrDefault("jobId")?.ToString() ?? "mock-copilot-job-00000001",
+            status = "Completed",
+            comments = new[]
+            {
+                new { line = 24, severity = "info", text = "Mock Copilot suggestion: tighten the parameter type." }
+            }
+        }
+    };
+}
diff --git a/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Config/ConfigHandlers.cs b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Config/ConfigHandlers.cs
new file mode 100644
index 00000000000..eb995af3e80
--- /dev/null
+++ b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Config/ConfigHandlers.cs
@@ -0,0 +1,149 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Azure.Sdk.Tools.Cli.Models;
+using Azure.Sdk.Tools.Cli.Models.Responses;
+using Azure.Sdk.Tools.Cli.Models.Responses.Codeowners;
+
+namespace Azure.Sdk.Tools.Mock.Handlers.Config;
+
+/// <summary>Mock handler for azsdk_check_service_label.</summary>
+public class CheckServiceLabelHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_check_service_label";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new ServiceLabelResponse
+    {
+        Label = arguments?.GetValueOrDefault("label")?.ToString() ?? "Contoso.WidgetManager",
+        Status = "Exists"
+    };
+}
+
+/// <summary>Mock handler for azsdk_create_service_label.</summary>
+public class CreateServiceLabelHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_create_service_label";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments)
+    {
+        var label = arguments?.GetValueOrDefault("label")?.ToString() ?? "Contoso.WidgetManager";
+        return new ServiceLabelResponse
+        {
+            Label = label,
+            Status = "Created",
+            PullRequestUrl = $"https://github.com/Azure/azure-sdk-tools/pull/99001"
+        };
+    }
+}
+
+/// <summary>Mock handler for azsdk_engsys_codeowner_view.</summary>
+public class CodeownerViewHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_engsys_codeowner_view";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new CodeownersViewResponse
+    {
+        Packages =
+        [
+            new PackageResponse
+            {
+                WorkItemId = 70001,
+                PackageName = "Azure.Template.Contoso",
+                Language = ".NET",
+                PackageType = "client",
+                Owners =
+                [
+                    new OwnerResponse { GitHubAlias = "contoso-owner-1" },
+                    new OwnerResponse { GitHubAlias = "contoso-owner-2" }
+                ],
+                Labels = ["Contoso.WidgetManager"]
+            }
+        ]
+    };
+}
+
+/// <summary>Mock handler for azsdk_engsys_codeowner_check_package.</summary>
+public class CodeownerCheckPackageHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_engsys_codeowner_check_package";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new CheckPackageResponse
+    {
+        DirectoryPath = arguments?.GetValueOrDefault("directoryPath")?.ToString() ?? "sdk/contoso/Azure.Template.Contoso",
+        Owners = ["contoso-owner-1", "contoso-owner-2"],
+        PRLabels = ["Contoso.WidgetManager"],
+        ServiceOwners = ["service-team-lead"],
+        ServiceLabels = ["Service Attention", "Contoso.WidgetManager"]
+    };
+}
+
+internal static class CodeownersModifyMockResponses
+{
+    public static CodeownersModifyResponse OkWithMessage() => new()
+    {
+        View = new CodeownersViewResponse
+        {
+            Packages =
+            [
+                new PackageResponse
+                {
+                    WorkItemId = 70001,
+                    PackageName = "Azure.Template.Contoso",
+                    Language = ".NET",
+                    PackageType = "client",
+                    Owners = [new OwnerResponse { GitHubAlias = "contoso-owner-1" }],
+                    Labels = ["Contoso.WidgetManager"]
+                }
+            ]
+        }
+    };
+}
+
+/// <summary>Mock handler for azsdk_engsys_codeowner_add_package_owner.</summary>
+public class CodeownerAddPackageOwnerHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_engsys_codeowner_add_package_owner";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => CodeownersModifyMockResponses.OkWithMessage();
+}
+
+/// <summary>Mock handler for azsdk_engsys_codeowner_add_package_label.</summary>
+public class CodeownerAddPackageLabelHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_engsys_codeowner_add_package_label";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => CodeownersModifyMockResponses.OkWithMessage();
+}
+
+/// <summary>Mock handler for azsdk_engsys_codeowner_add_label_owner.</summary>
+public class CodeownerAddLabelOwnerHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_engsys_codeowner_add_label_owner";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => CodeownersModifyMockResponses.OkWithMessage();
+}
+
+/// <summary>Mock handler for azsdk_engsys_codeowner_remove_package_owner.</summary>
+public class CodeownerRemovePackageOwnerHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_engsys_codeowner_remove_package_owner";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => CodeownersModifyMockResponses.OkWithMessage();
+}
+
+/// <summary>Mock handler for azsdk_engsys_codeowner_remove_package_label.</summary>
+public class CodeownerRemovePackageLabelHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_engsys_codeowner_remove_package_label";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => CodeownersModifyMockResponses.OkWithMessage();
+}
+
+/// <summary>Mock handler for azsdk_engsys_codeowner_remove_label_owner.</summary>
+public class CodeownerRemoveLabelOwnerHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_engsys_codeowner_remove_label_owner";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => CodeownersModifyMockResponses.OkWithMessage();
+}
+
+/// <summary>Mock handler for azsdk_engsys_codeowner_update_cache.</summary>
+public class CodeownerUpdateCacheHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_engsys_codeowner_update_cache";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new DefaultCommandResponse
+    {
+        Message = "CODEOWNERS cache refreshed (mock)",
+        Result = new { packagesRefreshed = 1, labelOwnersRefreshed = 1 }
+    };
+}
diff --git a/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Core/UpgradeHandler.cs b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Core/UpgradeHandler.cs
new file mode 100644
index 00000000000..71f767a7cb9
--- /dev/null
+++ b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Core/UpgradeHandler.cs
@@ -0,0 +1,23 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Azure.Sdk.Tools.Cli.Models;
+
+namespace Azure.Sdk.Tools.Mock.Handlers.Core;
+
+/// <summary>
+/// Mock handler for azsdk_upgrade. Always reports the current "mock" version is up to date so
+/// callers exercising the upgrade flow don't trigger a real download.
+/// </summary>
+public class UpgradeHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_upgrade";
+
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new UpgradeResponse
+    {
+        OldVersion = "0.0.0-mock",
+        NewVersion = "0.0.0-mock",
+        Message = "azsdk is already up to date (mock).",
+        RestartRequired = false
+    };
+}
diff --git a/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/EngSys/EngSysHandlers.cs b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/EngSys/EngSysHandlers.cs
new file mode 100644
index 00000000000..f0dce4fe65a
--- /dev/null
+++ b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/EngSys/EngSysHandlers.cs
@@ -0,0 +1,94 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Azure.Sdk.Tools.Cli.Models;
+using Azure.Sdk.Tools.Cli.Models.Responses;
+
+namespace Azure.Sdk.Tools.Mock.Handlers.EngSys;
+
+/// <summary>Mock handler for azsdk_analyze_log_file. Returns a single fake build error.</summary>
+public class AnalyzeLogFileHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_analyze_log_file";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new LogAnalysisResponse
+    {
+        Summary = "Detected one CS0246 compile error in the build log.",
+        SuggestedFix = "Add a `using Azure.Core;` directive at the top of the file.",
+        Errors =
+        [
+            new LogEntry
+            {
+                File = "src/Contoso.Widgets/Generated/WidgetsClient.cs",
+                Line = 42,
+                Message = "error CS0246: The type or namespace name 'WidgetOptions' could not be found"
+            }
+        ]
+    };
+}
+
+/// <summary>Mock handler for azsdk_get_failed_test_cases.</summary>
+public class GetFailedTestCasesHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_get_failed_test_cases";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new FailedTestRunListResponse
+    {
+        Items =
+        [
+            new FailedTestRunResponse
+            {
+                RunId = 100001,
+                TestCaseTitle = "Contoso.Widgets.Tests.WidgetClientLiveTests.GetWidget",
+                Outcome = "Failed",
+                ErrorMessage = "Expected status 200, got 404.",
+                StackTrace = "at Contoso.Widgets.Tests.WidgetClientLiveTests.GetWidget()"
+            }
+        ]
+    };
+}
+
+/// <summary>Mock handler for azsdk_get_failed_test_case_data.</summary>
+public class GetFailedTestCaseDataHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_get_failed_test_case_data";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new FailedTestRunResponse
+    {
+        RunId = 100001,
+        TestCaseTitle = arguments?.GetValueOrDefault("testCaseTitle")?.ToString()
+            ?? "Contoso.Widgets.Tests.WidgetClientLiveTests.GetWidget",
+        Outcome = "Failed",
+        ErrorMessage = "Expected status 200, got 404.",
+        StackTrace = "at Contoso.Widgets.Tests.WidgetClientLiveTests.GetWidget()",
+        Uri = "https://dev.azure.com/azure-sdk/internal/_test/cases?id=100001"
+    };
+}
+
+/// <summary>Mock handler for azsdk_get_failed_test_run_data.</summary>
+public class GetFailedTestRunDataHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_get_failed_test_run_data";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new FailedTestRunListResponse
+    {
+        Items =
+        [
+            new FailedTestRunResponse
+            {
+                RunId = int.TryParse(arguments?.GetValueOrDefault("runId")?.ToString(), out var id) ? id : 100001,
+                TestCaseTitle = "Contoso.Widgets.Tests.WidgetClientLiveTests.GetWidget",
+                Outcome = "Failed",
+                ErrorMessage = "Expected status 200, got 404.",
+                StackTrace = "at Contoso.Widgets.Tests.WidgetClientLiveTests.GetWidget()"
+            }
+        ]
+    };
+}
+
+/// <summary>Mock handler for azsdk_cleanup_ai_agents.</summary>
+public class CleanupAiAgentsHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_cleanup_ai_agents";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new DefaultCommandResponse
+    {
+        Message = "AI agents cleaned up (mock)",
+        Result = new { agentsDeleted = 3, threadsDeleted = 5 }
+    };
+}
diff --git a/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Example/ExampleAndDebugHandlers.cs b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Example/ExampleAndDebugHandlers.cs
new file mode 100644
index 00000000000..8ee1da1ba65
--- /dev/null
+++ b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Example/ExampleAndDebugHandlers.cs
@@ -0,0 +1,105 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Azure.Sdk.Tools.Cli.Models;
+
+namespace Azure.Sdk.Tools.Mock.Handlers.Example;
+
+/// <summary>
+/// Mock handler for azsdk_hello_world_fail. Always returns an error response so callers
+/// can exercise failure-path handling deterministically.
+/// </summary>
+public class HelloWorldFailHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_hello_world_fail";
+
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new DefaultCommandResponse
+    {
+        Message = "Simulated failure from azsdk_hello_world_fail",
+        ResponseError = "MOCK_HELLO_WORLD_FAIL"
+    };
+}
+
+/// <summary>
+/// Shared mock for all azsdk_example_* tools. Each tool maps to a fixed service name and operation
+/// label so callers can tell which path was exercised without changing the response shape.
+/// </summary>
+internal static class ExampleResponses
+{
+    public static CommandResponse Build(string serviceName, string operation, string result) =>
+        new ExampleServiceResponse
+        {
+            ServiceName = serviceName,
+            Operation = operation,
+            Result = result,
+            Details = new Dictionary<string, string>
+            {
+                ["mock"] = "true",
+                ["correlationId"] = "00000000-0000-0000-0000-000000000001"
+            }
+        };
+}
+
+public class ExampleAzureServiceHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_example_azure_service";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        ExampleResponses.Build("AzureStorage", "ListBlobs", "OK");
+}
+
+public class ExampleDevOpsServiceHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_example_devops_service";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        ExampleResponses.Build("AzureDevOps", "GetBuild", "OK");
+}
+
+public class ExampleGitHubServiceHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_example_github_service";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        ExampleResponses.Build("GitHub", "GetIssue", "OK");
+}
+
+public class ExampleAiServiceHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_example_ai_service";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        ExampleResponses.Build("AzureOpenAI", "Completion", "OK");
+}
+
+public class ExampleErrorHandlingHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_example_error_handling";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments)
+    {
+        var response = ExampleResponses.Build("ErrorHandling", "Simulated", "Failed");
+        response.ResponseError = "SIMULATED_ERROR";
+        return response;
+    }
+}
+
+public class ExampleProcessExecutionHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_example_process_execution";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        ExampleResponses.Build("Process", "sleep 1", "exit 0");
+}
+
+public class ExamplePowershellExecutionHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_example_powershell_execution";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        ExampleResponses.Build("PowerShell", "Get-Date", "exit 0");
+}
+
+public class ExampleAgentFibonacciHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_example_agent_fibonacci";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments)
+    {
+        var n = arguments?.GetValueOrDefault("n")?.ToString() ?? "10";
+        // 10th Fibonacci number; intentionally fixed so the mock is deterministic regardless of input.
+        return ExampleResponses.Build("AgentFibonacci", $"fib({n})", "55");
+    }
+}
diff --git a/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/GitHub/GitHubHandlers.cs b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/GitHub/GitHubHandlers.cs
new file mode 100644
index 00000000000..9a71f695a56
--- /dev/null
+++ b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/GitHub/GitHubHandlers.cs
@@ -0,0 +1,85 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Azure.Sdk.Tools.Cli.Models;
+using Azure.Sdk.Tools.Cli.Models.Responses.GitHub;
+
+namespace Azure.Sdk.Tools.Mock.Handlers.GitHub;
+
+/// <summary>Mock handler for azsdk_get_github_user_details.</summary>
+public class GetGitHubUserDetailsHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_get_github_user_details";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments)
+    {
+        var login = arguments?.GetValueOrDefault("userName")?.ToString() ?? "contoso-user";
+        return new DefaultCommandResponse
+        {
+            Message = $"Retrieved user details for {login}",
+            Result = new
+            {
+                login,
+                name = "Contoso User",
+                email = $"{login}@microsoft.com",
+                company = "Microsoft"
+            }
+        };
+    }
+}
+
+internal static class GitHubMockResponses
+{
+    public static PullRequestDetails ContosoPr(string? url = null) => new()
+    {
+        pullRequestNumber = 45001,
+        Author = "contoso-user",
+        Status = "open",
+        Url = url ?? "https://github.com/Azure/azure-sdk-for-net/pull/45001",
+        IsMerged = false,
+        IsMergeable = true,
+        Checks = ["ci: passed", "live-tests: pending"],
+        Comments = []
+    };
+}
+
+/// <summary>Mock handler for azsdk_get_pull_request_link_for_current_branch.</summary>
+public class GetPrLinkForCurrentBranchHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_get_pull_request_link_for_current_branch";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments)
+    {
+        var url = "https://github.com/Azure/azure-sdk-for-net/pull/45001";
+        return new GetPullRequestResponse
+        {
+            PullRequestUrl = url,
+            PullRequest = GitHubMockResponses.ContosoPr(url)
+        };
+    }
+}
+
+/// <summary>Mock handler for azsdk_create_pull_request.</summary>
+public class CreatePullRequestHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_create_pull_request";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new CreatePullRequestResponse
+    {
+        PullRequestUrl = "https://github.com/Azure/azure-sdk-for-net/pull/45002",
+        Messages = ["Pull request created (mock)"]
+    };
+}
+
+/// <summary>Mock handler for azsdk_get_pull_request.</summary>
+public class GetPullRequestHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_get_pull_request";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments)
+    {
+        var url = arguments?.GetValueOrDefault("pullRequestUrl")?.ToString()
+            ?? "https://github.com/Azure/azure-sdk-for-net/pull/45001";
+        return new GetPullRequestResponse
+        {
+            PullRequestUrl = url,
+            PullRequest = GitHubMockResponses.ContosoPr(url)
+        };
+    }
+}
diff --git a/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Package/PackageOperationHandlers.cs b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Package/PackageOperationHandlers.cs
new file mode 100644
index 00000000000..157e7ca4a13
--- /dev/null
+++ b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Package/PackageOperationHandlers.cs
@@ -0,0 +1,127 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Azure.Sdk.Tools.Cli.Models;
+using Azure.Sdk.Tools.Cli.Models.Responses.Package;
+
+namespace Azure.Sdk.Tools.Mock.Handlers.Package;
+
+internal static class PackageMockResponses
+{
+    public static PackageInfo ContosoPackage(string? language = null) => new()
+    {
+        PackageName = "Azure.Template.Contoso",
+        PackageVersion = "1.0.0-beta.1",
+        Language = language is null ? SdkLanguage.DotNet : SdkLanguageHelpers.GetSdkLanguage(language),
+        SdkType = SdkType.Dataplane
+    };
+}
+
+/// <summary>Mock handler for azsdk_package_generate_code.</summary>
+public class PackageGenerateCodeHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_package_generate_code";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        PackageOperationResponse.CreateSuccess(
+            "SDK code generated successfully (mock)",
+            PackageMockResponses.ContosoPackage(arguments?.GetValueOrDefault("language")?.ToString()),
+            typespecProjectPath: arguments?.GetValueOrDefault("typeSpecProjectPath")?.ToString());
+}
+
+/// <summary>Mock handler for azsdk_package_build_code.</summary>
+public class PackageBuildCodeHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_package_build_code";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        PackageOperationResponse.CreateSuccess(
+            "Package built successfully (mock)",
+            PackageMockResponses.ContosoPackage(arguments?.GetValueOrDefault("language")?.ToString()));
+}
+
+/// <summary>Mock handler for azsdk_package_run_tests.</summary>
+public class PackageRunTestsHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_package_run_tests";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        new TestRunResponse(exitCode: 0, testRunOutput: "Test run successful. 42 passed, 0 failed (mock).");
+}
+
+/// <summary>Mock handler for azsdk_package_run_check.</summary>
+public class PackageRunCheckHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_package_run_check";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        new PackageCheckResponse(
+            packageName: "Azure.Template.Contoso",
+            language: SdkLanguage.DotNet,
+            exitCode: 0,
+            checkStatusDetails: "All checks passed (mock).");
+}
+
+/// <summary>Mock handler for azsdk_package_pack.</summary>
+public class PackagePackHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_package_pack";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        PackageOperationResponse.CreateSuccess(
+            "Package archive created (mock)",
+            PackageMockResponses.ContosoPackage(arguments?.GetValueOrDefault("language")?.ToString()));
+}
+
+/// <summary>Mock handler for azsdk_package_update_version.</summary>
+public class PackageUpdateVersionHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_package_update_version";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        PackageOperationResponse.CreateSuccess(
+            $"Version updated to {arguments?.GetValueOrDefault("newVersion")?.ToString() ?? "1.0.0-beta.2"} (mock)",
+            PackageMockResponses.ContosoPackage(arguments?.GetValueOrDefault("language")?.ToString()));
+}
+
+/// <summary>Mock handler for azsdk_package_update_metadata.</summary>
+public class PackageUpdateMetadataHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_package_update_metadata";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        PackageOperationResponse.CreateSuccess(
+            "Metadata updated (mock)",
+            PackageMockResponses.ContosoPackage(arguments?.GetValueOrDefault("language")?.ToString()));
+}
+
+/// <summary>Mock handler for azsdk_package_update_changelog_content.</summary>
+public class PackageUpdateChangelogContentHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_package_update_changelog_content";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        PackageOperationResponse.CreateSuccess(
+            "Changelog updated (mock)",
+            PackageMockResponses.ContosoPackage(arguments?.GetValueOrDefault("language")?.ToString()));
+}
+
+/// <summary>Mock handler for azsdk_package_generate_samples.</summary>
+public class PackageGenerateSamplesHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_package_generate_samples";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments)
+    {
+        var resp = PackageOperationResponse.CreateSuccess(
+            "Samples generated (mock)",
+            PackageMockResponses.ContosoPackage(arguments?.GetValueOrDefault("language")?.ToString()));
+        resp.Result = new { samples_count = 3 };
+        return resp;
+    }
+}
+
+/// <summary>Mock handler for azsdk_package_translate_samples.</summary>
+public class PackageTranslateSamplesHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_package_translate_samples";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments)
+    {
+        var resp = PackageOperationResponse.CreateSuccess(
+            "Samples translated (mock)",
+            PackageMockResponses.ContosoPackage(arguments?.GetValueOrDefault("language")?.ToString()));
+        resp.Result = new { samples_count = 3 };
+        return resp;
+    }
+}
diff --git a/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Pipeline/AnalyzeAndArtifactsHandlers.cs b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Pipeline/AnalyzeAndArtifactsHandlers.cs
new file mode 100644
index 00000000000..5d72a7d130c
--- /dev/null
+++ b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Pipeline/AnalyzeAndArtifactsHandlers.cs
@@ -0,0 +1,66 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Azure.Sdk.Tools.Cli.Models;
+
+namespace Azure.Sdk.Tools.Mock.Handlers.Pipeline;
+
+/// <summary>Mock handler for azsdk_analyze_pipeline. Returns a fake-build summary with a single failed test + task.</summary>
+public class AnalyzePipelineHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_analyze_pipeline";
+
+    public CommandResponse Handle(Dictionary<string, object?>? arguments)
+    {
+        var buildId = arguments?.GetValueOrDefault("buildId")?.ToString() ?? "90001";
+        return new AnalyzePipelineResponse
+        {
+            PipelineUrl = $"https://dev.azure.com/azure-sdk/internal/_build/results?buildId={buildId}",
+            FailedTests = new Dictionary<string, List<string>>
+            {
+                ["Contoso.Widgets.Tests"] = ["WidgetClientLiveTests.GetWidget"]
+            },
+            FailedTasks =
+            [
+                new LogAnalysisResponse
+                {
+                    Summary = "1 test failure detected in WidgetClientLiveTests",
+                    SuggestedFix = "Check the live test recording for stale data and re-record.",
+                    Errors =
+                    [
+                        new LogEntry
+                        {
+                            File = "logs/test.log",
+                            Line = 128,
+                            Message = "Test WidgetClientLiveTests.GetWidget failed: expected 200 got 404"
+                        }
+                    ]
+                }
+            ]
+        };
+    }
+}
+
+/// <summary>Mock handler for azsdk_get_pipeline_llm_artifacts.</summary>
+public class GetPipelineLlmArtifactsHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_get_pipeline_llm_artifacts";
+
+    public CommandResponse Handle(Dictionary<string, object?>? arguments)
+    {
+        var buildId = arguments?.GetValueOrDefault("buildId")?.ToString() ?? "90001";
+        return new ObjectCommandResponse
+        {
+            Message = $"Retrieved LLM artifacts for build {buildId} (mock)",
+            Result = new
+            {
+                buildId,
+                artifacts = new[]
+                {
+                    new { name = "log-analysis.json", sizeBytes = 4096 },
+                    new { name = "failed-tests.json", sizeBytes = 2048 }
+                }
+            }
+        };
+    }
+}
diff --git a/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/ReleasePlan/ReleasePlanRemainingHandlers.cs b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/ReleasePlan/ReleasePlanRemainingHandlers.cs
new file mode 100644
index 00000000000..b092008b4db
--- /dev/null
+++ b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/ReleasePlan/ReleasePlanRemainingHandlers.cs
@@ -0,0 +1,133 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Azure.Sdk.Tools.Cli.Models;
+using Azure.Sdk.Tools.Cli.Models.AzureDevOps;
+using Azure.Sdk.Tools.Cli.Models.Responses.ReleasePlan;
+using Azure.Sdk.Tools.Cli.Models.Responses.ReleasePlanList;
+
+namespace Azure.Sdk.Tools.Mock.Handlers.ReleasePlan;
+
+internal static class ReleasePlanMockResponses
+{
+    public static ReleasePlanWorkItem ContosoWorkItem(string? typespecPath = null, string? releaseMonth = null) => new()
+    {
+        WorkItemId = 35000,
+        Title = "Release Plan - Contoso.WidgetManager",
+        Status = "Active",
+        Owner = "testuser@microsoft.com",
+        SDKReleaseMonth = releaseMonth ?? "06/2026",
+        ReleasePlanId = 50001,
+        IsDataPlane = true,
+        SpecType = "TypeSpec",
+        ActiveSpecPullRequest = "https://github.com/Azure/azure-rest-api-specs/pull/12345",
+        APISpecProjectPath = typespecPath ?? "specification/contosowidgetmanager/Contoso.WidgetManager",
+        SDKReleaseType = "beta",
+        SDKInfo =
+        [
+            new SDKInfo { Language = ".NET", PackageName = "Azure.Template.Contoso" },
+            new SDKInfo { Language = "Python", PackageName = "azure-contoso-widgetmanager" }
+        ]
+    };
+
+    public static ReleaseWorkflowResponse Workflow(string status, params string[] details) => new()
+    {
+        Language = SdkLanguage.DotNet,
+        Status = status,
+        TypeSpecProject = "specification/contosowidgetmanager/Contoso.WidgetManager",
+        Details = details.ToList()
+    };
+}
+
+/// <summary>Mock handler for azsdk_abandon_release_plan.</summary>
+public class AbandonReleasePlanHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_abandon_release_plan";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        ReleasePlanMockResponses.Workflow("Abandoned", "Release plan abandoned (mock)");
+}
+
+/// <summary>Mock handler for azsdk_update_release_plan.</summary>
+public class UpdateReleasePlanHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_update_release_plan";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new ReleasePlanResponse
+    {
+        TypeSpecProject = "specification/contosowidgetmanager/Contoso.WidgetManager",
+        PackageType = SdkType.Dataplane,
+        Message = "Release plan updated successfully (mock)",
+        ReleasePlanDetails = ReleasePlanMockResponses.ContosoWorkItem()
+    };
+}
+
+/// <summary>Mock handler for azsdk_get_release_plan_for_spec_pr.</summary>
+public class GetReleasePlanForSpecPrHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_get_release_plan_for_spec_pr";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new ReleasePlanResponse
+    {
+        TypeSpecProject = "specification/contosowidgetmanager/Contoso.WidgetManager",
+        PackageType = SdkType.Dataplane,
+        Message = "Release plan found for spec PR (mock)",
+        ReleasePlanDetails = ReleasePlanMockResponses.ContosoWorkItem()
+    };
+}
+
+/// <summary>Mock handler for azsdk_check_api_spec_ready_for_sdk.</summary>
+public class CheckApiSpecReadyForSdkHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_check_api_spec_ready_for_sdk";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        ReleasePlanMockResponses.Workflow("Ready", "API spec is signed off and ready for SDK generation (mock)");
+}
+
+/// <summary>Mock handler for azsdk_get_kpi_attestation_status.</summary>
+public class GetKpiAttestationStatusHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_get_kpi_attestation_status";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new ReleasePlanListResponse
+    {
+        ReleasePlanDetailsList = [ReleasePlanMockResponses.ContosoWorkItem()],
+        Message = "All required KPIs attested for this release (mock)."
+    };
+}
+
+/// <summary>Mock handler for azsdk_get_service_details_by_typespec_path.</summary>
+public class GetServiceDetailsByTypeSpecPathHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_get_service_details_by_typespec_path";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new ProductInfoResponse
+    {
+        ProductInfo = new ProductInfo
+        {
+            ProductServiceTreeId = "00000000-0000-0000-0000-000000000099",
+            ServiceId = "00000000-0000-0000-0000-000000000042",
+            PackageDisplayName = "Azure SDK for Contoso WidgetManager",
+            ProductServiceTreeLink = "https://servicetree.example.com/products/00000000-0000-0000-0000-000000000099",
+            WorkItemId = 36000,
+            Title = "Contoso.WidgetManager"
+        },
+        Message = "Product details resolved from TypeSpec path (mock)."
+    };
+}
+
+/// <summary>Mock handler for azsdk_update_api_spec_pull_request_in_release_plan.</summary>
+public class UpdateApiSpecPullRequestInReleasePlanHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_update_api_spec_pull_request_in_release_plan";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) =>
+        ReleasePlanMockResponses.Workflow(
+            "Updated",
+            "API spec pull request URL updated on release plan (mock)");
+}
+
+/// <summary>Mock handler for azsdk_update_language_exclusion_justification.</summary>
+public class UpdateLanguageExclusionJustificationHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_update_language_exclusion_justification";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new DefaultCommandResponse
+    {
+        Message = "Updated language exclusion justification in release plan (mock)."
+    };
+}
+
diff --git a/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/TypeSpec/TypeSpecHandlers.cs b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/TypeSpec/TypeSpecHandlers.cs
new file mode 100644
index 00000000000..29685abac32
--- /dev/null
+++ b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/TypeSpec/TypeSpecHandlers.cs
@@ -0,0 +1,130 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Azure.Sdk.Tools.Cli.Models;
+using Azure.Sdk.Tools.Cli.Models.AzureSdkKnowledgeAICompletion;
+using Azure.Sdk.Tools.Cli.Models.Responses.Package;
+using Azure.Sdk.Tools.Cli.Models.Responses.TypeSpec;
+
+namespace Azure.Sdk.Tools.Mock.Handlers.TypeSpec;
+
+internal static class TypeSpecMockResponses
+{
+    public const string ContosoTypeSpecProject = "specification/contosowidgetmanager/Contoso.WidgetManager";
+}
+
+/// <summary>Mock handler for azsdk_typespec_generate_authoring_plan.</summary>
+public class TypeSpecGenerateAuthoringPlanHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_typespec_generate_authoring_plan";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new TypeSpecAuthoringResponse
+    {
+        TypeSpecProject = TypeSpecMockResponses.ContosoTypeSpecProject,
+        Solution = "Add a new operation `GetWidgetById` to the WidgetService and bump the api-version.",
+        References =
+        [
+            new DocumentReference
+            {
+                Title = "TypeSpec authoring guide",
+                Source = "azure-rest-api-specs-wiki",
+                Link = "https://aka.ms/typespec-azure-guide"
+            }
+        ]
+    };
+}
+
+/// <summary>Mock handler for azsdk_typespec_init_project.</summary>
+public class TypeSpecInitProjectHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_typespec_init_project";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new TspToolResponse
+    {
+        TypeSpecProject = TypeSpecMockResponses.ContosoTypeSpecProject,
+        IsSuccessful = true,
+        NextSteps = ["Run `tsp compile .` to validate the new project."]
+    };
+}
+
+/// <summary>Mock handler for azsdk_convert_swagger_to_typespec.</summary>
+public class ConvertSwaggerToTypeSpecHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_convert_swagger_to_typespec";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new TspToolResponse
+    {
+        TypeSpecProject = TypeSpecMockResponses.ContosoTypeSpecProject,
+        IsSuccessful = true,
+        NextSteps =
+        [
+            "Review the converted TypeSpec for any TODOs.",
+            "Run `tsp compile .` to validate."
+        ]
+    };
+}
+
+/// <summary>Mock handler for azsdk_run_typespec_validation.</summary>
+public class RunTypeSpecValidationHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_run_typespec_validation";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new TypeSpecValidationResponse
+    {
+        TypeSpecProject = TypeSpecMockResponses.ContosoTypeSpecProject,
+        PackageType = SdkType.Dataplane,
+        Message = "TypeSpec validation passed (mock).",
+        validationResults = ["No issues found."]
+    };
+}
+
+/// <summary>Mock handler for azsdk_get_modified_typespec_projects.</summary>
+public class GetModifiedTypeSpecProjectsHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_get_modified_typespec_projects";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new ObjectCommandResponse
+    {
+        Message = "Found 1 modified TypeSpec project (mock).",
+        Result = new[] { TypeSpecMockResponses.ContosoTypeSpecProject }
+    };
+}
+
+/// <summary>Mock handler for azsdk_typespec_check_project_in_public_repo.</summary>
+public class TypeSpecCheckProjectInPublicRepoHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_typespec_check_project_in_public_repo";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new DefaultCommandResponse
+    {
+        Message = "TypeSpec project is present in the public azure-rest-api-specs repository (mock).",
+        Result = true
+    };
+}
+
+/// <summary>Mock handler for azsdk_typespec_delegate_apiview_feedback.</summary>
+public class TypeSpecDelegateApiViewFeedbackHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_typespec_delegate_apiview_feedback";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new DefaultCommandResponse
+    {
+        Message = "APIView feedback delegated to the TypeSpec author (mock).",
+        Result = new
+        {
+            commentsDelegated = 2,
+            assignee = "contoso-typespec-author"
+        }
+    };
+}
+
+/// <summary>Mock handler for azsdk_customized_code_update.</summary>
+public class CustomizedCodeUpdateHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_customized_code_update";
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new CustomizedCodeUpdateResponse
+    {
+        Success = true,
+        Message = "Customized code updated and rebuilt successfully (mock).",
+        AppliedPatches =
+        [
+            new AppliedPatch(
+                FilePath: "src/Generated/Customization/WidgetClientCustomization.cs",
+                Description: "Renamed Get to GetWidget",
+                ReplacementCount: 2)
+        ]
+    };
+}
diff --git a/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Verify/VerifySetupHandler.cs b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Verify/VerifySetupHandler.cs
new file mode 100644
index 00000000000..98edcd4d9cd
--- /dev/null
+++ b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/Handlers/Verify/VerifySetupHandler.cs
@@ -0,0 +1,34 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Azure.Sdk.Tools.Cli.Models;
+
+namespace Azure.Sdk.Tools.Mock.Handlers.Verify;
+
+/// <summary>
+/// Mock handler for azsdk_verify_setup. Returns an all-good response so downstream tools
+/// can proceed without environment prerequisites in mock mode.
+/// </summary>
+public class VerifySetupHandler : IMockToolHandler
+{
+    public string ToolName => "azsdk_verify_setup";
+
+    public CommandResponse Handle(Dictionary<string, object?>? arguments) => new VerifySetupResponse
+    {
+        Results =
+        [
+            new RequirementCheckResult
+            {
+                Requirement = "dotnet",
+                Instructions = ["dotnet SDK is installed."],
+                RequirementStatusDetails = "dotnet 8.0.100 detected"
+            },
+            new RequirementCheckResult
+            {
+                Requirement = "git",
+                Instructions = ["git is installed."],
+                RequirementStatusDetails = "git 2.45.0 detected"
+            }
+        ]
+    };
+}
diff --git a/tools/azsdk-cli/Azure.Sdk.Tools.Mock/README.md b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/README.md
index ea326f81f17..45e12ba2bf5 100644
--- a/tools/azsdk-cli/Azure.Sdk.Tools.Mock/README.md
+++ b/tools/azsdk-cli/Azure.Sdk.Tools.Mock/README.md
@@ -115,3 +115,14 @@ This lets callers control the mock behavior through input:
 - `{"message": "Alice"}` → normal success response
 
 Use this pattern in any handler to test how your integration handles different scenarios without changing the mock server code.
+
+## Keeping the Mock in Sync with the Live MCP Server
+
+The mock reuses the live CLI's tool definitions (`SharedOptions.ToolsList`), so the *set* of advertised tools is always identical. What can drift is which tools have a hand-written `IMockToolHandler`. Tools without a handler fall back to the generic `{"message":"Success"}` default — fine for routing tests but useless for scenarios that chain calls together (e.g. consume an ID returned by a previous tool).
+
+When you add or rename an MCP tool in `Azure.Sdk.Tools.Cli`, add a matching handler under `Handlers/<Domain>/`:
+
+1. Look up the live tool's response type under `tools/azsdk-cli/Azure.Sdk.Tools.Cli/Tools/`. The return type is usually a typed `CommandResponse` in `Azure.Sdk.Tools.Cli.Models.Responses.*`.
+2. Create a new file under `Handlers/<Domain>/` (e.g., `Handlers/Pipeline/MyToolHandler.cs`).
+3. Implement `IMockToolHandler`. Set `ToolName` to the exact `[McpServerTool(Name = "…")]` value from the real tool.
+4. Return an instance of the same response type the real tool returns, populated with realistic sample data. For scenarios that need to exercise multiple branches, switch on `arguments` (see `HelloWorldHandler` above).