Avoid propagating server tool exception message to client (#242)

Co-authored-by: Eirik Tsarpalis <[email protected]>

Author: stephentoub

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" }],
             };
         }
 

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]