Imporove signal list tests, use structured tool results for signal listing

Author: Nicholas Blumhardt

src/SeqCli/Mcp/Tools/Search/SearchAndQueryToolType.cs

@@ -331,7 +331,7 @@ public Task NewSessionAsync(CancellationToken cancellationToken)
         return Task.CompletedTask;
     }
 
-    [McpServerTool(Name = "seq_list_signals", ReadOnly = true, Title = "List Signals")]
+    [McpServerTool(Name = "seq_list_signals", ReadOnly = true, Title = "List Signals", UseStructuredContent = true)]
     [Description("List available signals. Use signals when searching and querying to efficiently work with well-known " +
                  "event streams while dramatically improving response times.")]
     public async Task<SignalSummary[]> ListSignalsAsync(CancellationToken cancellationToken)

test/SeqCli.EndToEnd/Mcp/McpSignalUsageTestCase.cs

@@ -12,11 +12,13 @@ namespace SeqCli.EndToEnd.Mcp;
 // ReSharper disable once UnusedType.Global
 public class McpSignalUsageTestCase : McpToolTestCase
 {
+    record SignalSummary(string Id, string Title);
+
     // Default signals included in every Seq installation.
-    const string Errors = "signal-m33301";
-    const string Warnings = "signal-m33302";
-    const string Spans = "signal-m20231011";
-    const string Logs = "signal-m20231211";
+    static readonly SignalSummary Errors = new("signal-m33301", "Errors");
+    static readonly SignalSummary Warnings = new("signal-m33302", "Warnings");
+    static readonly SignalSummary Spans = new("signal-m20231011", "Spans");
+    static readonly SignalSummary Logs = new("signal-m20231211", "Logs");
 
     protected override async Task ExecuteAsync(SeqConnection connection, ILogger logger, McpClient client)
     {
@@ -28,27 +30,27 @@ protected override async Task ExecuteAsync(SeqConnection connection, ILogger log
         logger.Warning("Item {ItemNumber} delayed in run {RunId}", 4, runId);
         logger.Error("Item {ItemNumber} failed in run {RunId}", 5, runId);
 
-        var signalsResult = AssertTextResult(await client.CallToolAsync("seq_list_signals"));
+        var signals = AssertStructuredResult<SignalSummary[]>(await client.CallToolAsync("seq_list_signals"));
         foreach (var signal in new[] { Errors, Warnings, Spans, Logs })
         {
-            Assert.Contains(signal, signalsResult);
+            Assert.Contains(signal, signals);
         }
 
         var predicate = $"RunId = '{runId}' and @Timestamp >= Now() - 1d";
 
         // Union: the two warnings plus the error.
-        Assert.Equal(3, await CountSearchResultsAsync(client, predicate, $"{Errors}~{Warnings}"));
+        Assert.Equal(3, await CountSearchResultsAsync(client, predicate, $"{Errors.Id}~{Warnings.Id}"));
 
         // Intersection: all of the warnings are log events, not spans.
-        Assert.Equal(2, await CountSearchResultsAsync(client, predicate, $"{Warnings},{Logs}"));
+        Assert.Equal(2, await CountSearchResultsAsync(client, predicate, $"{Warnings.Id},{Logs.Id}"));
 
         var query = $"select count(*) as total from stream where {predicate}";
 
         // Union: no spans were written, so only the error is counted.
-        Assert.Equal(1, await CountQueryResultAsync(client, query, $"{Spans}~{Errors}"));
+        Assert.Equal(1, await CountQueryResultAsync(client, query, $"{Spans.Id}~{Errors.Id}"));
 
         // Intersection with a grouped union: warnings and errors, all of which are log events.
-        Assert.Equal(3, await CountQueryResultAsync(client, query, $"({Errors}~{Warnings}),{Logs}"));
+        Assert.Equal(3, await CountQueryResultAsync(client, query, $"({Errors.Id}~{Warnings.Id}),{Logs.Id}"));
     }
 
     static async Task<int> CountSearchResultsAsync(McpClient client, string predicate, string signal)

test/SeqCli.EndToEnd/Mcp/McpToolTestCase.cs

@@ -1,4 +1,5 @@
 using System.Linq;
+using System.Text.Json;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using ModelContextProtocol.Client;
@@ -39,6 +40,17 @@ protected static string AssertTextResult(CallToolResult callToolResult)
         return text;
     }
 
+    protected static T AssertStructuredResult<T>(CallToolResult callToolResult)
+    {
+        AssertTextResult(callToolResult);
+        Assert.NotNull(callToolResult.StructuredContent);
+
+        // Tools returning non-object values have them wrapped in a `result` property by the MCP
+        // SDK, because the protocol requires `structuredContent` to be an object.
+        var result = callToolResult.StructuredContent.Value.GetProperty("result");
+        return JsonSerializer.Deserialize<T>(result, JsonSerializerOptions.Web)!;
+    }
+
     protected static string[] OrderedSearchResultIds(string searchResult)
     {
         return ResultIdRegex().Matches(searchResult).Select(m => m.Value).Distinct().ToArray();