Fixed nested value envelope in MCP stored procedure responses

src/Azure.DataApiBuilder.Mcp/BuiltInTools/ExecuteEntityTool.cs

@@ -381,22 +381,7 @@ private static CallToolResult BuildExecuteSuccessResponse(
             // Handle different result types
             if (queryResult is OkObjectResult okResult && okResult.Value != null)
             {
-                // Extract the actual data from the action result
-                if (okResult.Value is JsonDocument jsonDoc)
-                {
-                    JsonElement root = jsonDoc.RootElement;
-                    responseData["value"] = root.ValueKind == JsonValueKind.Array ? root : JsonSerializer.SerializeToElement(new[] { root });
-                }
-                else if (okResult.Value is JsonElement jsonElement)
-                {
-                    responseData["value"] = jsonElement.ValueKind == JsonValueKind.Array ? jsonElement : JsonSerializer.SerializeToElement(new[] { jsonElement });
-                }
-                else
-                {
-                    // Serialize the value directly
-                    JsonElement serialized = JsonSerializer.SerializeToElement(okResult.Value);
-                    responseData["value"] = serialized;
-                }
+                responseData["value"] = McpResponseBuilder.NormalizeStoredProcedureResult(okResult.Value);
             }
             else if (queryResult is BadRequestObjectResult badRequest)
             {

src/Azure.DataApiBuilder.Mcp/Core/DynamicCustomTool.cs

@@ -580,22 +580,7 @@ private static CallToolResult BuildExecuteSuccessResponse(
             // Handle different result types
             if (queryResult is OkObjectResult okResult && okResult.Value != null)
             {
-                // Extract the actual data from the action result
-                if (okResult.Value is JsonDocument jsonDoc)
-                {
-                    JsonElement root = jsonDoc.RootElement;
-                    responseData["value"] = root.ValueKind == JsonValueKind.Array ? root : JsonSerializer.SerializeToElement(new[] { root });
-                }
-                else if (okResult.Value is JsonElement jsonElement)
-                {
-                    responseData["value"] = jsonElement.ValueKind == JsonValueKind.Array ? jsonElement : JsonSerializer.SerializeToElement(new[] { jsonElement });
-                }
-                else
-                {
-                    // Serialize the value directly
-                    JsonElement serialized = JsonSerializer.SerializeToElement(okResult.Value);
-                    responseData["value"] = serialized;
-                }
+                responseData["value"] = McpResponseBuilder.NormalizeStoredProcedureResult(okResult.Value);
             }
             else if (queryResult is BadRequestObjectResult badRequest)
             {

src/Azure.DataApiBuilder.Mcp/Utils/McpResponseBuilder.cs

@@ -102,6 +102,30 @@ public static string ExtractResultJson(IActionResult? result)
             }
         }
 
+        /// <summary>
+        /// Normalizes a stored procedure result to an array, unwrapping the DAB response envelope when present.
+        /// </summary>
+        public static JsonElement NormalizeStoredProcedureResult(object value)
+        {
+            JsonElement result = value switch
+            {
+                JsonDocument document => document.RootElement,
+                JsonElement element => element,
+                _ => JsonSerializer.SerializeToElement(value)
+            };
+
+            if (result.ValueKind == JsonValueKind.Object &&
+                result.TryGetProperty("value", out JsonElement valueArray) &&
+                valueArray.ValueKind == JsonValueKind.Array)
+            {
+                return valueArray.Clone();
+            }
+
+            return result.ValueKind == JsonValueKind.Array
+                ? result.Clone()
+                : JsonSerializer.SerializeToElement(new[] { result });
+        }
+
         /// <summary>
         /// Extracts value from a JsonElement.
         /// </summary>

src/Service.Tests/Mcp/DynamicCustomToolMsSqlIntegrationTests.cs

@@ -82,13 +82,9 @@ public async Task DynamicCustomTool_GetBookById_ReturnsMatchingRecord()
 
             Assert.IsTrue(root.TryGetProperty("value", out JsonElement valueWrapper), "Response should contain 'value' property.");
 
-            JsonElement records = valueWrapper.ValueKind == JsonValueKind.Object
-                ? valueWrapper.GetProperty("value")
-                : valueWrapper;
-
-            Assert.AreEqual(JsonValueKind.Array, records.ValueKind);
-            Assert.IsTrue(records.GetArrayLength() > 0, "Expected at least one book record.");
-            Assert.AreEqual(1, records[0].GetProperty("id").GetInt32());
+            Assert.AreEqual(JsonValueKind.Array, valueWrapper.ValueKind);
+            Assert.IsTrue(valueWrapper.GetArrayLength() > 0, "Expected at least one book record.");
+            Assert.AreEqual(1, valueWrapper[0].GetProperty("id").GetInt32());
         }
 
         /// <summary>

src/Service.Tests/Mcp/DynamicCustomToolTests.cs

@@ -554,6 +554,25 @@ public async Task ExecuteAsync_JsonDocumentObjectResult_WrapsValueInArray()
             Assert.AreEqual(JsonValueKind.Array, response.RootElement.GetProperty("value").ValueKind);
         }
 
+        [DataTestMethod]
+        [DataRow("[]", DisplayName = "Empty result")]
+        [DataRow("[{\"id\":1},{\"id\":2}]", DisplayName = "Multiple rows")]
+        [DataRow("[{\"id\":1,\"value\":[\"first\",{\"nested\":\"second\"}]}]", DisplayName = "Array-valued value column")]
+        public async Task ExecuteAsync_EngineResponse_RemovesOnlyOuterEnvelope(string rowsJson)
+        {
+            using JsonDocument rows = JsonDocument.Parse(rowsJson);
+            CallToolResult result = await ExecuteCustomToolAsync(
+                dbParameters: new(),
+                userParameters: null,
+                queryOutcome: SqlResponseHelpers.OkResponse(rows.RootElement.Clone()));
+
+            AssertSuccess(result, "The DAB response envelope should be removed from the stored procedure result.");
+            using JsonDocument response = JsonDocument.Parse(GetFirstText(result));
+            JsonElement value = response.RootElement.GetProperty("value");
+            Assert.AreEqual(JsonValueKind.Array, value.ValueKind);
+            Assert.AreEqual(JsonSerializer.Serialize(rows.RootElement), JsonSerializer.Serialize(value), "Rows should be unchanged after removing only the engine envelope.");
+        }
+
         [TestMethod]
         public async Task ExecuteAsync_PocoResult_IsSerialized()
         {

src/Service.Tests/Mcp/ExecuteEntityToolMsSqlIntegrationTests.cs

@@ -76,13 +76,9 @@ public async Task ExecuteEntity_GetBookById_ReturnsMatchingRecord()
 
             Assert.IsTrue(root.TryGetProperty("value", out JsonElement valueWrapper), "Response should contain 'value' property.");
 
-            JsonElement records = valueWrapper.ValueKind == JsonValueKind.Object
-                ? valueWrapper.GetProperty("value")
-                : valueWrapper;
-
-            Assert.AreEqual(JsonValueKind.Array, records.ValueKind);
-            Assert.IsTrue(records.GetArrayLength() > 0, "Expected at least one book record.");
-            Assert.AreEqual(1, records[0].GetProperty("id").GetInt32());
+            Assert.AreEqual(JsonValueKind.Array, valueWrapper.ValueKind);
+            Assert.IsTrue(valueWrapper.GetArrayLength() > 0, "Expected at least one book record.");
+            Assert.AreEqual(1, valueWrapper[0].GetProperty("id").GetInt32());
         }
 
         /// <summary>

src/Service.Tests/Mcp/ExecuteEntityToolTests.cs

@@ -538,6 +538,26 @@ public async Task ExecuteEntity_ObjectJsonResult_IsWrappedInArray()
             Assert.AreEqual(1, value[0].GetProperty("id").GetInt32());
         }
 
+        [DataTestMethod]
+        [DataRow("[]", DisplayName = "Empty result")]
+        [DataRow("[{\"id\":1},{\"id\":2}]", DisplayName = "Multiple rows")]
+        [DataRow("[{\"id\":1,\"value\":[\"first\",{\"nested\":\"second\"}]}]", DisplayName = "Array-valued value column")]
+        public async Task ExecuteEntity_EngineResponse_RemovesOnlyOuterEnvelope(string rowsJson)
+        {
+            using JsonDocument rows = JsonDocument.Parse(rowsJson);
+            CallToolResult result = await ExecuteWithMockedEngineAsync(
+                TEST_ENTITY,
+                new(),
+                null,
+                queryOutcome: SqlResponseHelpers.OkResponse(rows.RootElement.Clone()));
+
+            AssertSuccess(result, "The DAB response envelope should be removed from the stored procedure result.");
+            using JsonDocument response = JsonDocument.Parse(GetFirstText(result));
+            JsonElement value = response.RootElement.GetProperty("value");
+            Assert.AreEqual(JsonValueKind.Array, value.ValueKind);
+            Assert.AreEqual(JsonSerializer.Serialize(rows.RootElement), JsonSerializer.Serialize(value), "Rows should be unchanged after removing only the engine envelope.");
+        }
+
         [TestMethod]
         public async Task ExecuteEntity_UnknownResult_ReturnsEmptyValue()
         {