From 1f126d92fdb9dfba13cf895d69ee4366ce7f0169 Mon Sep 17 00:00:00 2001
From: Stephen Toub <stoub@microsoft.com>
Date: Tue, 8 Apr 2025 21:43:59 -0400
Subject: [PATCH] Avoid propagating server tool exception message to client

---
 src/ModelContextProtocol/Server/AIFunctionMcpServerTool.cs      | 2 +-
 .../Configuration/McpServerBuilderExtensionsToolsTests.cs       | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/ModelContextProtocol/Server/AIFunctionMcpServerTool.cs b/src/ModelContextProtocol/Server/AIFunctionMcpServerTool.cs
index 0f33c8e41..ad37f37d6 100644
--- a/src/ModelContextProtocol/Server/AIFunctionMcpServerTool.cs
+++ b/src/ModelContextProtocol/Server/AIFunctionMcpServerTool.cs
@@ -270,7 +270,7 @@ public override async Task<CallToolResponse> InvokeAsync(
             return new CallToolResponse()
             {
                 IsError = true,
-                Content = [new() { Text = e.Message, Type = "text" }],
+                Content = [new() { Text = $"An error occurred invoking '{request.Params?.Name}'.", Type = "text" }],
             };
         }
 
diff --git a/tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsToolsTests.cs b/tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsToolsTests.cs
index a93a3090e..57e6eb818 100644
--- a/tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsToolsTests.cs
+++ b/tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsToolsTests.cs
@@ -376,7 +376,7 @@ public async Task Returns_IsError_Content_When_Tool_Fails()
         Assert.True(result.IsError);
         Assert.NotNull(result.Content);
         Assert.NotEmpty(result.Content);
-        Assert.Contains("Test error", result.Content[0].Text);
+        Assert.Contains("An error occurred", result.Content[0].Text);
     }
 
     [Fact]