Merge task branch for: fix(worker): external MCP optional params are generated as required; errors are opaque

src/ClaudeDo.Worker/External/ConfigMcpTools.cs

@@ -31,7 +31,8 @@ public sealed class ConfigMcpTools
 
     [McpServerTool, Description("Set a list's default model/system prompt/agent path/max turns. Passing all four as null clears the list config.")]
     public async Task SetListConfig(
-        string listId, string? model, string? systemPrompt, string? agentPath, int? maxTurns, CancellationToken cancellationToken)
+        string listId, string? model = null, string? systemPrompt = null, string? agentPath = null,
+        int? maxTurns = null, CancellationToken cancellationToken = default)
     {
         _ = await _lists.GetByIdAsync(listId, cancellationToken)
             ?? throw new InvalidOperationException($"List {listId} not found.");
@@ -53,7 +54,8 @@ public sealed class ConfigMcpTools
 
     [McpServerTool, Description("Set per-task config overrides (model/system prompt/agent path/max turns). Pass null for any field to clear that override.")]
     public async Task SetTaskConfig(
-        string taskId, string? model, string? systemPrompt, string? agentPath, int? maxTurns, CancellationToken cancellationToken)
+        string taskId, string? model = null, string? systemPrompt = null, string? agentPath = null,
+        int? maxTurns = null, CancellationToken cancellationToken = default)
     {
         _ = await _tasks.GetByIdAsync(taskId, cancellationToken)
             ?? throw new InvalidOperationException($"Task {taskId} not found.");

src/ClaudeDo.Worker/External/ExternalMcpExceptionFilter.cs

@@ -0,0 +1,32 @@
+using ModelContextProtocol;
+using ModelContextProtocol.Protocol;
+using ModelContextProtocol.Server;
+
+namespace ClaudeDo.Worker.External;
+
+/// <summary>
+/// The MCP SDK's own call-tool catch-all only preserves ex.Message for <see cref="McpException"/> —
+/// any other exception type is replaced with a generic "An error occurred invoking 'X'." with no detail.
+/// This filter translates the expected validation exceptions thrown across the External/ tool classes
+/// (task/list not found, bad status, unknown model, etc.) into McpException so callers see why a call failed.
+/// </summary>
+public static class ExternalMcpExceptionFilter
+{
+    public static McpRequestHandler<CallToolRequestParams, CallToolResult> Wrap(
+        McpRequestHandler<CallToolRequestParams, CallToolResult> next) =>
+        async (request, cancellationToken) =>
+        {
+            try
+            {
+                return await next(request, cancellationToken);
+            }
+            catch (InvalidOperationException ex)
+            {
+                throw new McpException(ex.Message, ex);
+            }
+            catch (ArgumentException ex)
+            {
+                throw new McpException(ex.Message, ex);
+            }
+        };
+}

src/ClaudeDo.Worker/External/ExternalMcpService.cs

@@ -107,9 +107,9 @@ public sealed class ExternalMcpService
         "Valid status values: Idle, Queued, Running, WaitingForReview, WaitingForChildren, Done, Failed, Cancelled.")]
     public async Task<IReadOnlyList<TaskDto>> ListTasks(
         string listId,
-        string? createdBy,
-        string? status,
-        CancellationToken cancellationToken)
+        string? createdBy = null,
+        string? status = null,
+        CancellationToken cancellationToken = default)
     {
         TaskStatus? statusFilter = null;
         if (!string.IsNullOrWhiteSpace(status))
@@ -193,10 +193,10 @@ public sealed class ExternalMcpService
     [McpServerTool, Description("Update an existing task's title, description, and/or commit type. Pass null to leave a field unchanged. Refuses if the task is currently Running.")]
     public async Task<TaskDto> UpdateTask(
         string taskId,
-        string? title,
-        string? description,
-        string? commitType,
-        CancellationToken cancellationToken)
+        string? title = null,
+        string? description = null,
+        string? commitType = null,
+        CancellationToken cancellationToken = default)
     {
         var task = await _tasks.GetByIdAsync(taskId, cancellationToken)
             ?? throw new InvalidOperationException($"Task {taskId} not found.");
@@ -219,8 +219,8 @@ public sealed class ExternalMcpService
     public async Task<TaskDto> AddSubtask(
         string taskId,
         string title,
-        int? orderNum,
-        CancellationToken cancellationToken)
+        int? orderNum = null,
+        CancellationToken cancellationToken = default)
     {
         if (string.IsNullOrWhiteSpace(title))
             throw new InvalidOperationException("title is required.");
@@ -300,8 +300,8 @@ public sealed class ExternalMcpService
     public async Task<TaskDto> ReviewTask(
         string taskId,
         string decision,
-        string? feedback,
-        CancellationToken cancellationToken)
+        string? feedback = null,
+        CancellationToken cancellationToken = default)
     {
         _ = await _tasks.GetByIdAsync(taskId, cancellationToken)
             ?? throw new InvalidOperationException($"Task {taskId} not found.");
@@ -619,8 +619,8 @@ public sealed class ExternalMcpService
     public async Task<TaskDto> SetMyDay(
         string taskId,
         bool isMyDay,
-        int? sortOrder,
-        CancellationToken cancellationToken)
+        int? sortOrder = null,
+        CancellationToken cancellationToken = default)
     {
         await using var ctx = await _dbFactory.CreateDbContextAsync(cancellationToken);
 

src/ClaudeDo.Worker/External/ListMcpTools.cs

@@ -22,7 +22,7 @@ public sealed class ListMcpTools
 
     [McpServerTool, Description("Create a new task list. workingDir sets the git repo tasks run against; commitType defaults to 'chore'.")]
     public async Task<ListSummaryDto> CreateList(
-        string name, string? workingDir, string? commitType, CancellationToken cancellationToken)
+        string name, string? workingDir = null, string? commitType = null, CancellationToken cancellationToken = default)
     {
         if (string.IsNullOrWhiteSpace(name))
             throw new InvalidOperationException("name is required.");
@@ -42,7 +42,8 @@ public sealed class ListMcpTools
 
     [McpServerTool, Description("Rename a list and/or change its working dir and default commit type. Pass null to leave a field unchanged.")]
     public async Task<ListSummaryDto> UpdateList(
-        string listId, string? name, string? workingDir, string? commitType, CancellationToken cancellationToken)
+        string listId, string? name = null, string? workingDir = null, string? commitType = null,
+        CancellationToken cancellationToken = default)
     {
         var entity = await _lists.GetByIdAsync(listId, cancellationToken)
             ?? throw new InvalidOperationException($"List {listId} not found.");