Surface downstream MCP ServerInfo and instructions to consumers

Directory.Build.props

@@ -1,7 +1,7 @@
 <Project>
 
   <PropertyGroup>
-    <Version>0.2.0</Version>
+    <Version>0.3.0</Version>
   </PropertyGroup>
 
 </Project>

src/McpAggregator.Core/Models/RegisteredServer.cs

@@ -10,4 +10,10 @@ public class RegisteredServer
     public DateTimeOffset RegisteredAt { get; set; } = DateTimeOffset.UtcNow;
     public bool HasSkillDocument { get; set; }
     public string? AiSummary { get; set; }
+
+    // Metadata captured from the downstream MCP server on connection.
+    public string? RemoteName { get; set; }
+    public string? RemoteTitle { get; set; }
+    public string? RemoteVersion { get; set; }
+    public string? RemoteInstructions { get; set; }
 }

src/McpAggregator.Core/Models/ServiceIndex.cs

@@ -8,6 +8,13 @@ public class ServiceIndex
     public bool Enabled { get; set; }
     public bool Available { get; set; }
     public bool HasSkillDocument { get; set; }
+
+    // Identity reported by the downstream MCP server's ServerInfo (compact identity only;
+    // the full server-supplied instructions are surfaced via ServiceDetails).
+    public string? RemoteName { get; set; }
+    public string? RemoteTitle { get; set; }
+    public string? RemoteVersion { get; set; }
+
     public List<ToolSummary> Tools { get; set; } = [];
 }
 
@@ -25,6 +32,13 @@ public class ServiceDetails
     public bool Enabled { get; set; }
     public bool Available { get; set; }
     public bool HasSkillDocument { get; set; }
+
+    // Metadata supplied by the downstream MCP server itself during the initialize handshake.
+    public string? RemoteName { get; set; }
+    public string? RemoteTitle { get; set; }
+    public string? RemoteVersion { get; set; }
+    public string? RemoteInstructions { get; set; }
+
     public List<ToolDetail> Tools { get; set; } = [];
     public List<PromptDetail> Prompts { get; set; } = [];
 }

src/McpAggregator.Core/Services/ConnectionManager.cs

@@ -204,6 +204,22 @@ private async Task<ConnectionState> ConnectAsync(RegisteredServer server, Cancel
         _connections[server.Name] = state;
         AggregatorTelemetry.ActiveConnections.Add(1, new TagList { { "server_name", server.Name } });
         _logger.LogInformation("Connected to '{Server}'", server.Name);
+
+        try
+        {
+            await _registry.UpdateRemoteMetadataAsync(
+                server.Name,
+                client.ServerInfo?.Name,
+                client.ServerInfo?.Title,
+                client.ServerInfo?.Version,
+                client.ServerInstructions,
+                ct);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogDebug(ex, "Failed to capture remote metadata from '{Server}'", server.Name);
+        }
+
         return state;
     }
 

src/McpAggregator.Core/Services/ServerRegistry.cs

@@ -105,6 +105,31 @@ public async Task UpdateSummaryAsync(string name, string summary, CancellationTo
         await PersistAsync(ct);
     }
 
+    public async Task UpdateRemoteMetadataAsync(
+        string name,
+        string? remoteName,
+        string? remoteTitle,
+        string? remoteVersion,
+        string? remoteInstructions,
+        CancellationToken ct = default)
+    {
+        var server = Get(name);
+        if (server.RemoteName == remoteName
+            && server.RemoteTitle == remoteTitle
+            && server.RemoteVersion == remoteVersion
+            && server.RemoteInstructions == remoteInstructions)
+        {
+            return;
+        }
+
+        server.RemoteName = remoteName;
+        server.RemoteTitle = remoteTitle;
+        server.RemoteVersion = remoteVersion;
+        server.RemoteInstructions = remoteInstructions;
+        await PersistAsync(ct);
+        _logger.LogDebug("Updated remote metadata for '{Name}' (version: {Version})", name, remoteVersion ?? "unknown");
+    }
+
     public async Task SetEnabledAsync(string name, bool enabled, CancellationToken ct = default)
     {
         var server = Get(name);

src/McpAggregator.Core/Services/SummaryGenerator.cs

@@ -58,13 +58,29 @@ public SummaryGenerator(
                     """;
             }
 
+            var serverIdentity = string.IsNullOrWhiteSpace(server.RemoteTitle)
+                ? server.RemoteName
+                : $"{server.RemoteTitle} ({server.RemoteName})";
+
+            var instructionsSection = string.IsNullOrWhiteSpace(server.RemoteInstructions)
+                ? ""
+                : $"""
+
+
+                    Server-supplied instructions (authoritative — these come from the server itself
+                    and describe how it expects to be used; weight this heavily over names alone):
+                    {server.RemoteInstructions}
+                    """;
+
             var userContent = $"""
                 Server name: {server.Name}
                 Display name: {server.DisplayName ?? "(none)"}
-                Description: {server.Description ?? "(none)"}
+                Registered description: {server.Description ?? "(none)"}
+                Remote identity: {serverIdentity ?? "(none)"}
+                Remote version: {server.RemoteVersion ?? "(none)"}
 
                 Tools:
-                {toolList}{promptSection}
+                {toolList}{promptSection}{instructionsSection}
                 """;
 
             using var cts = CancellationTokenSource.CreateLinkedTokenSource(ct);
@@ -74,12 +90,18 @@ public SummaryGenerator(
                 [
                     new(ChatRole.System, """
                         You are a technical indexer building a capability index for an AI agent orchestrator.
-                        Given an MCP server's metadata, tool catalog, and prompt templates, produce a concise
-                        summary (2-4 sentences, max 300 characters) that describes what this server does and
-                        what capabilities it offers. The summary will be read by another AI agent deciding
-                        whether to route a request to this server, so use precise technical language and
-                        emphasize what kinds of tasks or domains this server handles. If prompt templates
-                        are present, mention them as first-class capabilities alongside tools.
+                        Given an MCP server's metadata, tool catalog, prompt templates, and any
+                        server-supplied instructions, produce a concise summary (2-4 sentences,
+                        max 300 characters) that describes what this server does and what capabilities
+                        it offers. The summary will be read by another AI agent deciding whether to
+                        route a request to this server, so use precise technical language and emphasize
+                        what kinds of tasks or domains this server handles.
+
+                        When server-supplied instructions are present, treat them as the authoritative
+                        description of the server's purpose and recommended use — they override
+                        guesses inferred from tool names. If prompt templates are present, mention them
+                        as first-class capabilities alongside tools.
+
                         Output ONLY the summary text, no quotes or labels.
                         """),
                     new(ChatRole.User, userContent)

src/McpAggregator.Core/Services/ToolIndex.cs

@@ -96,6 +96,11 @@ public async Task<List<ServiceIndex>> GetIndexAsync(CancellationToken ct = defau
                 }
             }
 
+            // Populate after the tools call so a fresh connect has refreshed the cached metadata.
+            index.RemoteName = server.RemoteName;
+            index.RemoteTitle = server.RemoteTitle;
+            index.RemoteVersion = server.RemoteVersion;
+
             results.Add(index);
         }
 
@@ -126,6 +131,10 @@ public async Task<ServiceDetails> GetDetailsAsync(string serverName, Cancellatio
             Enabled = server.Enabled,
             Available = true,
             HasSkillDocument = server.HasSkillDocument,
+            RemoteName = server.RemoteName,
+            RemoteTitle = server.RemoteTitle,
+            RemoteVersion = server.RemoteVersion,
+            RemoteInstructions = server.RemoteInstructions,
             Tools = tools,
             Prompts = prompts
         };

test/McpAggregator.Core.Tests/Services/SummaryGeneratorTests.cs

@@ -171,4 +171,40 @@ public async Task GenerateSummaryAsync_SendsCorrectPromptContent()
         Assert.IsTrue(userText.Contains("tool_a"), "User prompt should contain tool names");
         Assert.IsTrue(userText.Contains("tool_b"), "User prompt should contain tool names");
     }
+
+    [TestMethod]
+    public async Task GenerateSummaryAsync_IncludesRemoteMetadataAndInstructions()
+    {
+        IEnumerable<ChatMessage>? capturedMessages = null;
+        var expectations = new IChatClientCreateExpectations();
+        expectations.Setups.GetResponseAsync(
+                Arg.Any<IEnumerable<ChatMessage>>(),
+                Arg.IsDefault<ChatOptions?>(),
+                Arg.Any<CancellationToken>())
+            .Callback((messages, _, _) =>
+            {
+                capturedMessages = messages;
+                return Task.FromResult(new ChatResponse(new ChatMessage(ChatRole.Assistant, "Summary")));
+            });
+        var client = expectations.Instance();
+        var gen = CreateGenerator(chatClient: client, enabled: true);
+
+        var server = SampleServer();
+        server.RemoteName = "weather-api";
+        server.RemoteTitle = "Weather API";
+        server.RemoteVersion = "2.3.1";
+        server.RemoteInstructions = "Use get_forecast for multi-day predictions and get_current for now-only queries.";
+
+        await gen.GenerateSummaryAsync(server, SampleTools());
+
+        Assert.IsNotNull(capturedMessages);
+        var userText = capturedMessages!.ToList()[1].Text;
+        Assert.IsNotNull(userText);
+        Assert.IsTrue(userText!.Contains("Weather API"), "User prompt should contain remote title");
+        Assert.IsTrue(userText.Contains("weather-api"), "User prompt should contain remote name");
+        Assert.IsTrue(userText.Contains("2.3.1"), "User prompt should contain remote version");
+        Assert.IsTrue(userText.Contains("get_forecast"), "User prompt should contain remote instructions verbatim");
+        Assert.IsTrue(userText.Contains("Server-supplied instructions"),
+            "User prompt should label the instructions section");
+    }
 }