Files
ClaudeDo/tests/ClaudeDo.Worker.Tests/External/ExternalMcpToolSchemaTests.cs
T
mika kuns d7ebafd556 fix(worker): make external MCP filter params optional, surface tool errors
Nullable filter/patch params across the External/ MCP tool classes (ListTasks,
UpdateTask, AddSubtask, ReviewTask, SetMyDay, SetListConfig/SetTaskConfig,
CreateList/UpdateList) lacked C# default values, so the generated tool schema
marked them required — MCP clients omitting them (the common case) failed.
Gave every such parameter a default value.

Also registered a call-tool filter (ExternalMcpExceptionFilter) on the external
MCP host that translates InvalidOperationException/ArgumentException into
McpException, since the SDK's own catch-all discards ex.Message for any other
exception type and returns a generic "An error occurred invoking 'X'." string.

Added a reflection-based schema test sweeping every [McpServerToolType] class
to guard against reintroducing a required-but-nullable parameter.
2026-07-23 18:21:46 +02:00

75 lines
3.2 KiB
C#

using System.Reflection;
using ClaudeDo.Worker.External;
using Microsoft.Extensions.AI;
using ModelContextProtocol.Server;
namespace ClaudeDo.Worker.Tests.External;
/// <summary>
/// MCP clients routinely omit optional arguments. The generated tool schema only marks a
/// parameter optional when the C# method declares a default value — nullability alone is not
/// enough (verified against ModelContextProtocol/Microsoft.Extensions.AI 1.2.0 / 10.4.1's
/// AIJsonUtilities.CreateFunctionJsonSchema, which checks ParameterInfo.IsOptional). This sweeps
/// every [McpServerToolType] class in the External/ namespace so a future tool can't reintroduce
/// a nullable-but-required filter parameter.
/// </summary>
public sealed class ExternalMcpToolSchemaTests
{
private static IEnumerable<MethodInfo> ExternalToolMethods()
{
var toolTypes = typeof(ExternalMcpService).Assembly.GetTypes()
.Where(t => t.Namespace == typeof(ExternalMcpService).Namespace
&& t.GetCustomAttribute<McpServerToolTypeAttribute>() is not null);
foreach (var type in toolTypes)
foreach (var method in type.GetMethods(BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly))
{
if (method.GetCustomAttribute<McpServerToolAttribute>() is not null)
yield return method;
}
}
[Fact]
public void NoExternalTool_HasARequiredNullableParameter()
{
var nullabilityContext = new NullabilityInfoContext();
var violations = new List<string>();
foreach (var method in ExternalToolMethods())
{
var schema = AIJsonUtilities.CreateFunctionJsonSchema(method);
var required = schema.TryGetProperty("required", out var requiredElement)
? requiredElement.EnumerateArray().Select(e => e.GetString()).ToHashSet()
: new HashSet<string?>();
foreach (var parameter in method.GetParameters())
{
if (parameter.ParameterType == typeof(CancellationToken)) continue;
if (!required.Contains(parameter.Name)) continue;
var isNullableValueType = Nullable.GetUnderlyingType(parameter.ParameterType) is not null;
var isNullableRefType = !parameter.ParameterType.IsValueType
&& nullabilityContext.Create(parameter).WriteState == NullabilityState.Nullable;
if (isNullableValueType || isNullableRefType)
{
violations.Add(
$"{method.DeclaringType!.Name}.{method.Name}({parameter.Name}) is a nullable " +
"type but has no default value, so MCP clients omitting it will fail. " +
"Give it a default value (e.g. '= null').");
}
}
}
Assert.True(violations.Count == 0, string.Join(Environment.NewLine, violations));
}
[Fact]
public void ExternalToolMethods_AreDiscovered()
{
// Guards the sweep itself: if this drops to 0, ExternalToolMethods() broke silently
// (e.g. namespace/attribute mismatch) and the schema test above would pass vacuously.
Assert.True(ExternalToolMethods().Count() > 20);
}
}